Reverse Dictionary: FOOL


FOOL – adjectives (also see FOOLISH)
– BILLY-WHIFFLING playing the fool …Bk1898 Eng. dial.
fool – nouns 
– BOOBOLOGY the study of fools …Bk1942 Amer. sl.
– DORK-FACTOR the number of fools …1970s US campus sl.
– FEATHER IN THE CAP, A † the badge of a fool …a1700
– FOOLOLOGY. the study of fools …Bk1942 Amer. sl.
– JACKASSIFICATION n. the act of making a jackass or fool of …1822 nonce word
– MOROLOGY the science that treats of fools …1867 humorous
– NUTOLOGY the study of fools …Bk1942 Amer. sl.
fool – person (includes foolish person)
– AARDVARK a slow-witted person having a coarse or foolish appearance; an oaf; a fool …1968 Amer. sl.
– A.B. fools as a group (Asshole Brigade) …1980s sl.
– ABRAM a gullible fool; a cuckold …1639 UK sl.
– ACE a foolish or ineffectual person; a clumsy person; an oaf, a jerk: used sarcastically …1969 US campus sl.
– ACROBAT a fool …1958 W. Indies sl.
– ADDLE-BRAIN a stupid or half-witted fellow; a foolish bungler; a dullard …1880
– ADDLE COVE a foolish man; an easy dupe …Bk1898 Eng. dial.
– ADDLE-PATE a stupid bungler; a dullard; a weak, silly person; a foolish person; an easy dupe …1601
– ADGER a foolish, silly person: used playfully to children …Bk1905 Eng. dial.
– AH-AH a stupid person; a fool …1928 Amer. dial.
– AIREDALE a fool; a worthless person; a pest …1920s US sl.
– AIRHEAD a foolish person …1972 sl., orig. & chiefly US
– AL a fool, a jester; a silly person …1857 Eng. dial.
– ALEC a fool or simpleton …1919 Aust. sl.
– ALECK a foolish person …1944 Aust. sl.
– ALKITHOLE a foolish fellow …1746 Eng. dial.
– ALKITOTLE a foolish fellow …1746 Eng. dial.
– ALLYAUN a fool …Irish sl.
– AMADAN a foolish person …Irish sl.
– AMADAUN a foolish person …Irish sl.
– AMATON a foolish person; one yielding to anger …B1900 Sc.
– AMITAN a weak, foolish person …Bk1911 Sc.
– AMOTH a big soft fool who would cry for nothing …1878 Ireland
– ANIMAL a fool; an oaf; a stupid person …L16
– APE † a foolish person who imitates …c1330
– APPLEHEAD. a fool …1940s US sl.
– APPLE-JOHN a foolish and probably impotent old man …L16 sl.
– APPLE-KNOCKER a fool …1930s sl.
– APPLE-PICKER a fool, an unsophisticated person, a country person …1910s US sl.
– ARBUCKLE a fool …20C teen & high school sl.
– ARSE a stupid, unpleasant, or contemptible person; a fool …c1785
– ARSEHOLE, ASSHOLE a foolish or despicable person; an unpleasant person, usually male …c1784
– ARSEWIPE (derogatory) a foolish or contemptible person …1962 sl.
– ASS a foolish or stupid person …c1450 colloq.
– ASSHEAD a stupid or foolish person; an idiot …a1500 colloq.
– ASSINEGER a fool, a simpleton, a stupid person …Bk1898 Eng. dial.
– ASSINEGO a fool, a simpleton, a stupid person …Bk1898 Eng. dial.
– ASSNEGER a fool, a simpleton, a stupid person …Bk1898 Eng. dial.
– ASSWIPE (derogatory) a foolish or contemptible person …1953 sl. 
– ATTWOOD a foolish fellow; a stupid person; a blockhead; a simpleton …1894 Eng. dial.
– AUF. AWF a foolish person, a simpleton …1750 Eng. dial.
– BAARIE a fool; one who has newly arrived at a township from the countryside …1977 S. Afr. sl.
– BABBY-LAKER one who entertains foolish speculations …Bk1898 Eng. dial.
– BABE * an adult regarded as being like a child in some way; a childish or foolish person; an inexperienced, naive, or innocent person …1542
– BABELAVANTE  a foolish or absurd person …a1400
– BABION  (derogatory) a term of contempt for a person; a stupid or foolish person …a1529
– BABOON (derogatory) a foolish, stupid, or contemptible person; a person considered to resemble a baboon in appearance; an ugly or uncouth person; an oaf, a jerk; often as a term of abuse …1592
– BABY (often derogatory) an immature, foolish or childish person …1539
– BACON-BRAINS a fool, a stupid clodhopper, a clownish blockhead …a1634
– BADAUD a booby, a fool …Bk1894
– BAFOON a term of abuse, a fool …1989 sl.
– BAKE a fool, an idiot …1860 US sl.
– BAKEBRAIN (derogatory) someone with limited or damaged mental faculties; a fool, an idiot; a stupid person …1949 US sl.
– BAKEHEAD a fool, an idiot; a stupid person; an insane or crazy person  …1949 US sl.
– BALDERDASH a fool …1821 Anglo-Irish
– BALLITRAUNT  a foolish person; a buffoon; used as a term of contempt …1790 Eng. dial.
– BALLOCKS a fool; a term of abuse; one who is performing or talking ‘ballocks’ or nonsense …1916 sl.
– BALLOON a bully, a garrulous person, one full of hot air; a self-important or boastful idiot; a fool …1965 Sc. & Irish English colloq.
– BALLOON-BRAIN a fool, a simpleton; a silly, empty-headed person …1949 US sl. 
– BALLOON HEAD an arrogant, conceited, or stupid person; a fool, a simpleton, a silly, empty-headed person …1931 colloq., chiefly US
– BALMY a fool, a simpleton; a soft, weak-minded person …1887 Eng. dial.
– BAM a foolish, annoying, or obnoxious person; a belligerent or disruptive person; often used as a contemptuous form of address …1959 Sc. colloq.
– BAMPOT a foolish, annoying, or obnoxious person; a belligerent or disruptive person; an eccentric person; often used as a contemptuous form of address …1962 Sc. colloq.
– BAMSTICK a foolish, annoying, or obnoxious person; a belligerent or disruptive person; often used as a contemptuous form of address …1965 Sc. colloq.
– BANANA BENDER a fool …1992 UK sl.
– BANANAHEAD a simpleton, a fool, an idiot, a stupid person …1949 US sl.
– BAPHEAD a fool …2001 UK teen sl.
– BARBER a tediously talkative person; a fool, esp. in sports usage …1927 US sl.
– BARI a fool; one who has newly arrived at a township from the countryside …1970s S. Afr. sl.
– BARM-HEAD a soft, foolish person …1865 Eng. dial.
– BARMPOT a foolish person …1951 Brit. sl., orig. N. Eng. dial.
– BARMY a fool, a simpleton …1887 Eng. dial.
– BARN-DOOR SAVAGE a countryman; a rustic; a yokel; a foolish, awkward, or clumsy person …1876 sl.
– BARRIE, BARRY a fool; one who has newly arrived at a township from the countryside …1977 S. Afr. sl.
– BASTOON a fool…1827 Irish sl.
– BAT a silly, foolish, thoughtless, or worthless person …1870 US sl.
– BATBRAIN a fool or a crazy person …1937 US sl.
– BATHEAD a fool or a crazy person …1942 US sl.
– BATIE-BUM † (derogatory) a lazy or inactive fellow; an idler; a simpleton, a fool; a useless bungler …1572 Sc. 
– BATIE-BUMMIL † an inactive helpless fellow; a useless bungler; a simpleton; a fool…a1550 Sc.
– BATTERLASH a small-witted person; a foolish or gullible person …1867 Eng. dial.
– BAUBLE † a childish or foolish person; a silly trifler …a1606
– BAVIAN * (derogatory) a fool, an idiot …1797
– BAWCOCK a foolish person …1795 Eng. dial.
– BAZIL † a drunkard, a sot; a fool …1816 Sc.
– BAZOO a lout; a fool; an easy victim …1929 US sl.
– BAZOOKA a fool …1950 UK sl.
– BAZOONUS a lout; a fool …1903 US sl.
– BAZZONUS a lout; a fool …1929 US sl.
– B.B. a bird-brain; a fool, a stupid person; one of low intelligence; a slow-witted person …1958 US sl.
– BB STACKER a stupid person; a fool …1960 US sl.
– BEALS a fool, an idiot, an unsophisticated person; a displeasing person …a2001 sl.
– BEAN a term of disparagement for a foolish, unpleasant or obnoxious person …1915 US sl.
– BEANBRAIN a fool; a simpleton; a stupid oaf …1953 US sl.
– BEANHEAD a dull, stupid person; a fool; an oaf …1919 Amer. sl.
– BEARDLESS WONDER an incompetent or foolish person …1952 US sl.
– BEAR’S ASS a fool; an ignoramus …1969 US college sl.
– BEECHAM’S (PILL) a fool, a simpleton …1952 Aust. rhyming sl. for ‘dill’
– BEE EFF a foolish person, a ‘bloody fool’ …1925 sl., orig. Brit. services’ usage
– BEEF-BRAIN a thug; a fool …1989 US sl.
– BEEFHEAD a thickhead, a blockhead, a fool …1775
– BEE-IN-THE-BONNET an eccentric; a flighty person; a foolish person …1856 Sc. & Eng. dial.
– BEERY BUFF a fool …1960 UK rhyming sl. for ‘muff’
– BEETLE a crazy, eccentric, or foolish person; a madman, an obsessive fan …1605 sl.
– BEETLE-BRAIN (derogatory) a person of low intelligence; a stupid person; a blockhead; a fool; a dolt …1593
– BEETLEBROW a blockhead; a fool …1850 sl.
– BEETLE-HEAD (derogatory) a person of low intelligence; a blockhead; a fool, a stupid person …1577
– BEGUNK a fool …1895 Sc.
– BEHEMA a fool …Bk1982 Jewish
– BEL-SHANGLE a fool …1847 UK sl.
– BEN a simpleton, a fool …c1698 UK criminals’ sl.
– BEND a foolish, foppish fellow …Bk1898 Sc.
– BERK a despicable person; a stupid or offensive person; a disliked person; a fool …1929 Brit. rhyming sl. for ‘cunt’ (Berkeley Hunt)
– BERKELEY (HUNT) a fool; a person whom one does not like; an incompetent …1937 Brit. rhyming sl. for ‘cunt’
– BERKSHIRE HUNT a fool; a person whom one does not like …1960 Brit. rhyming sl. for ‘cunt’ 
– BESOM-HEAD a foolish or stupid person; a blockhead …1864
– BEZOM-HEAD a foolish, stupid person …1889 Eng. dial.
– B.F. a foolish person, a ‘bloody fool’ …1894 sl.
– BIFF a fool …2003 UK sl.
– BIG BLAH a fool; an idiot …1927 US sl.
– BIG BOY a foolish, reckless, devil-may-care young man; a loveable idiot …1922 US Black sl.
– BIG-BWOY an affectionate term for a foolish person …1995 W. Indies
– BIG CHEESE – a foolish, obnoxious, or inept person; anyone who has pretensions to being smart …1918 US sl.
– BIG STIFF a term of abuse; a fool; a rough, clumsy, stupid, or overbearing man; a mean, disagreeable or contemptible person; a disliked person; an uncouth, self-opinionated person …1896 sl., orig. US
– BILLY a fool …1786 Sc. & UK criminals’ sl.
– BILLY BARLOW a half-witted street fool; a street clown; a mountebank …1835 UK sl.
– BILLY BUTTON a gullible fool, esp. one who performs a job of work without first making sure that they will be paid …1996 W. Indies rhyming sl. for ‘gets nothing’
– BILLYGOAT an incompetent, silly person; a fool …Bk1988 Aust. sl. 
– BILLY-MINAWKY a foolish or stupid fellow, a booby …Bk1887 Eng. dial.
– BILLY MUGGINS a fool …1910s Aust. sl. 
– BILLY-WHIFFLER a fool; a simpleton …Bk1898 Eng. dial.
– BINLID a stupid person; a fool …Bk1997 Ulster sl.
– BIRD-BRAIN a person with a small brain; one of low intelligence; a frivolous, scatterbrained person; a fool; a stupid person …1933
– BIRK a fool; a stupid or slow-thinking person …1929 sl.
– BISH a fool, a stupid person, a dope …1963 US teen sl.
– BIZZUM-HEAD a person who is equally foolish and stupid …Bk1855 Eng. dial.
– BLADDER MOUTH a coarse, noisy talker, devoid of sense; a noisy fool …Bk1886 Eng. dial.
– BLADDERSKATE a silly foolish person; a babbler …a1680 Sc.
– BLADDERSKYTE a silly foolish person …Bk1876 Sc.
– BLAH a fool, an idiot …1923 US sl.
– BLAITIE BUM  (derogatory) a lazy or feckless person; an idler; a simpleton, a fool, a bungler; a sheepish fellow …1540 Sc.
– BLEEDER a ‘bloody fool’ …1890 sl.
– BLELLUM a foolish, talkative person; an idle chatterer …1787 Sc.
– BLOB a foolish person …1916 sl., chiefly Aust.
– BLOCK a fool, an idiot, a stupid person …M16 sl.
– BLOCKHEAD a foolish person …1549
– BLUNNERBOAR a blundering fool …Bk1911 Sc.
– BOGAN a fool, an idiot …Aust. sl.
– BOINARD † a fool, a simpleton; a rogue, a rascal, a scoundrel, a low person; a term of reproach …a1300
– BOOB a foolish person …1907 sl.
– BOOBY a foolish person …1599 sl.
– BOOFHEAD a fool; a very gullible person …c1930 Aust. sl.
– BORN-HEAD a young precocious fellow; a very foolish person …Bk1911 Sc.
– BOSTHOON a fool or blockhead …1914 Irish sl.
– BOSTOON a fool or blockhead …1914 Irish sl.
– BOZO a clumsy, clownish, or foolish fellow; an oaf; a rude or annoying person …1916 Amer. sl.
– BRACK-BRAIN a fool …Bk2006 US sl.
– BROWNMOUTH a talkative fool …1991 Irish sl.
– BUFFER a foolish old person …1749 Brit. sl.
– BUFFLEHEAD a fool, a blockhead, a simpleton, a stupid person, a silly person, an ignoramus …1659
– BUGGERLUGS an annoying or foolish person; chiefly used as an affectionate form of address, or mild term of reproof …1861 sl.
– BURG a fool, an idiot; an unpleasant person …1980s S. Afr.
– BURK(E) a foolish person …1936 sl., chiefly Brit.
– BUTTERBRAIN a fool …1975-78 Amer. sl.
– BUTTERED BUN a country fool; a rustic simpleton …E18 sl.
– BUTTERHEAD a fool …1963 US sl.
– BUTTHOLE a foolish or despicable person; an obnoxious person …1962 Amer. sl.
– BUZZARD a foolish or despicable person; a contemptible old man …1641
– CA a soft, foolish person …1825 Sc. 
– CABBAGE-HEAD a fool; a soft-head; a stupid person …1682 sl.
– CAKE a fool or dullard; a stupid fellow …1785 Eng. dial. & sl.
– CAKEHEAD an idiot; a fool …1998 UK sl.
– CAKEY a fool or dullard …L18 sl.
– CAKUM a foolish person …Bk1898 Eng. dial.
– CALF a fool, a simpleton; a stupid or loutish person; an awkward or silly boy or man; a meek, harmless person …1553 sl.
– CALF-HEAD a foolish fellow …Bk1898 Eng. dial.
– CALF’S HEAD a fool; a very stupid fellow …L16 sl.
– CALONKUS a fool …L19 Aust. sl.
– CANG † a fool …a1225
– CANK † a fool …a1225
– CARLE-GROPUS  a stupid person; a fool …1866 Sc.
– CARTOON a ridiculous person; a fool …1927 Amer. sl.
– CATHEAD a fool …1950s US sl.
– CEMENTHEAD a blockhead, a fool, a stupid person …1949 Amer. sl.
– CHANG † a fool …a1225
– CHANK † a fool …a1225
– CHARLEY, CHARLIE a foolish person …1946 sl., chiefly Brit.
– CHEESEHEAD a fool; a stupid person …20C teen & high school sl.
– CHEESE MEISTER  a fool; a jerk …20C teen & high school sl.
– CHERRY PICKER an ignorant rustic; a fool …1929 US sl.
– CHICKENBRAIN a fool …1922 US sl.
– CHICKEN’S HEAD a fool …1960s US Black sl.
– CHIEF a general insult; a fool, a braggart …1990s UK Black sl.
– CHOOCH a blockhead, a fool …1971 Italian-American
– CHOWDAR a fool …Bk1892 Anglo-Chinese
– CHOWDERBRAIN a fool, a stupid person …1960 US sl.
– CHOWDERHEAD a stupid person, a fool, a blockhead; a muddle-headed person; a dunce … 1682 sl.
– CHUCKLEHEAD a fool; a silly person; a stupid person …1731
– CHUMP a fool; a soft-head; anyone gullible or easily taken in …1682 sl.
– CHUMPIE a fool; anyone gullible or easily taken in …L19 sl.
– CHUMP OF WOOD a fool; a soft-head …Bk1891 sl.
– CHUPIDEE, CHUPIDDY, CHUPIDIE, CHUPIDY a gullible, ignorant fool …20C W. Indies sl.
– CLODPOLE, CLODPOLL a foolish person …1601 Brit.
– CLOT a fool; an oaf …19C colloq.
– CLOT-HEAD a fool; an oaf …19C colloq.
– CLOUTER-HEAD a foolish, stupid person; one deficient in understanding …c1861 Eng. dial.
– CLUCK a stupid oaf; a fool …20C US colloq.
– CLUNK a foolish person …1942 US sl.
– COCK-A-LILTY a person talking or acting foolishly …19C Eng. dial.
– COCKAMAMIE, COCKAMAMY a foolish or ridiculous person …1936 US sl.
– COCKAMANIE, COCKAMANY a foolish or ridiculous person …1936 US sl.
– COCKSCOMB a fool; a fop or dandy …L16
– COD a fool …L17 sl.
– CODFISH a fool …L18 sl.
– COD’S-HEAD a stupid fellow, a fool, a blockhead; a dupe …1566
– COD’S HEAD AND SHOULDERS a dupe; a fool …19C sl.
– COISTRIL, CUSTREL * a worthless or contemptible person; a knave, a rogue; later, a cowardly or timorous person; a foolish or inexperienced youth …1570 arch.
– COKES a fool …M16 sl.
– CONEHEAD a fool; an oaf …Bk2006 US sl.
– COOT a foolish or crotchety person, esp. one who is old …colloq.
– COXCOMB a fool; a fop or dandy …L16
– CRACKBRAIN a fool; a stupid oaf …Bk2006 US sl.
– CRACKERJACK a fool, an oaf …1970s US campus sl.
– CRATEHEAD a fool, an idiot …Bk2004 sl.
– CUTER a fool; a josh …Bk1914 criminals’ sl.
– D.A. a fool, an idiot (Dumb-Ass) …1970s US campus sl.
– DACEHEAD a fool …E19 sl.
– DAFF † one deficient in sense or in proper spirit; a simpleton, a fool; a coward …c1325 obs. exc. N. Eng. dial.
– DAFFAM a fool, a silly person …Bk1828 Eng. dial.
– DAFFE  a stupid, foolish person …c1325
– DAFF(E)Y a fool, a silly person …1867 Eng. dial.
– DAFT DORIS a foolish woman …2000 UK sl.
– DAFT-HEAD a silly fellow; an idiot; a fool …Bk1873 Eng. dial.
– DAFTIE a simpleton; a fool …1868 Sc. & Eng. dial.
– DAFT WATTY a silly, awkward person; a foolish fellow; a blockhead …1805 Eng. dial.
– DAMFOOL a damned fool …c1880 colloq.
– DAMN-FOOL a damned fool …19C colloq.
– DAMPHOOL(E), DAMPHULE a damned fool …c1880 colloq.
– DAMWIT a fool …1940s US sl.
– DAN a fool (Dumb-Ass Nigger) …2000s US Black sl.
– DAPHNE a foolish woman …1980s Aust. sl.
– DARB a fool …1920s sl.
– DARK a fool; a dullard …1960s US campus sl.
– DASIBERD † a stupid fellow, a fool, a dullard, a simpleton … c1400
– DATE a foolish, silly, stupid, or weak person …1914 UK sl.
– DAW † a silly, chattering person, a simpleton, a fool …c1500 obs. exc. Eng. dial.
– DAWCOCK † a stupid, silly, awkward fellow, a simpleton, a fool …1556 obs. exc. Eng. dial.
– DAWKIN a dull, stupid person, a simpleton, a fool …1565 Eng. dial.
– DAWPATE † a silly fellow, a simpleton, a fool …a1529
– DEADHEAD a fool; a stupid person …1930s Black sl.
– DEAD ONE a fool …L19 US sl.
– DICKEY-DIDO an idiot; a fool…19C Brit. sl.
– DICK-HEAD a foolish person …1964 sl.
– DILBERRY a fool …1952 NZ sl.
– DILL a fool …1941 Aust. sl.
– DILLPOT a fool …1941 Aust. rhyming sl. for ‘twat’
– DILLYPOT a fool …1941 Aust. rhyming sl. for ‘twat’
– DIMELOW a fool, an idiot …1900 UK sl.
– DIMWIT a slow-witted fool …1921 US sl.
– DINDERHEAD a foolish person …1867 Eng. dial.
– DINELO, DINELOW a fool, an idiot …1900 UK sl.
– DING-A-LING a fool; an oaf; an odd, giddy person who hears bells …1935 US sl.
– DINGBAT a dull, stupid person; a fool; a silly or light-headed person …1915  Amer. dial.
– DINGDONG a dull, stupid person; a fool; an oaf; a silly or light-headed person …1929 Amer. sl.
– DINGLEBERRY a foolish person …1924 sl., orig. US
– DINGLEBODY a foolish, simple person …1957 US sl.
– DIP a foolish person …1932 US sl.
– DIPSHIT a foolish person …1962 US sl.
– DIPSTICK an inept fool; an idiot; a jerk; a stupid or contemptible person; an oaf …1963 US sl.
– DIRK a foolish, peculiar, or obnoxious person; an absent-minded or inattentive person; a jerk …1964 US sl.
– DIVVY, DIVY a foolish person …1989 Brit. sl.
– DIZ, DIZZ a foolish person …1963 US sl.
– DIZZARD † a foolish, stupid, or silly fellow; an idiot, a blockhead; a weak-minded person …1547 obs. or arch.
– DOBBIE a stupid fellow; a blockhead, a fool, a simpleton, a dolt; a childish old man, a dotard; an awkward fellow, a clown …1677 Sc. & Eng. dial.
– DODDY-PATE † a stupid person, a blockhead, a fool, a dunce …c1500 obs. exc. Eng. dial.
– DODE a fool …1989 US sl.
– DODO a fool; an unintelligent person …1898 US colloq.
– DOE a fool, a simpleton, a dupe …1961 US sl.
– DOES (taboo) a foolish or despicable person …S. Afr. sl.
– DOITARD a simpleton, a fool, an idiot …1860 Eng. dial.
– DOITY a fool, simpleton, idiot …19C Eng. dial.
– DOLLYPOT an oaf; a fool …1920s Aust. rhyming sl. for ‘twat’
– DONKEY a foolish person …Bk1913-17 Amer. dial.
– DOOBIE a dull, stupid fellow; a fool, a simpleton; a dunce …19C Sc.
– DOODLE-BRAIN a general insult; a stupid person, a fool …1990s Aust. teen sl.
– DOODLE-HEAD a general insult; a stupid person, a fool …1990s Aust. teen sl.
– DOOF a fool, a simpleton, an oaf …1970s US sl.
– DOOFUS an oaf, a fool …M20 US sl.
– DOORKNOB a fool …1930s sl.
– DOPE a foolish person …1851 sl.
– DORK a foolish person …1967 sl., chiefly US
– DORKUS a fool …1979 US sl.
– DORKUS MAXIMUS a simpleton; a great fool …Bk2006 US sl.
– DOTARD a weak-minded or foolish old person …a1393
– DOUGH-HEAD a fool …Bk1905 Amer. dial.
– DRONGO a stupid, foolish, or incompetent person …1941 Aust. & NZ sl.
– DROOB a stupid fool …Bk1999 Aust. sl.
– DROOP an ineffectual, incompetent, or languid person; a fool …1932 US sl.
– DUCK EGG a fool …2003 UK sl.
– DUDE a foolish or obnoxious fellow …1967 US sl.
– DUDHEAD a fool, a dolt …1963 US sl.
– DUFFER an incompetent person; a person of no ability; a foolish oaf; a bungler …c1730 UK sl.
– DUFFUS a fool, a dolt, an oaf …1978 US sl.
– DULL-HEAD † a dull-headed or slow-witted person; a fool, a blockhead …1534
– DULL-PATE † a dull-headed or slow-witted person; a fool, a blockhead …a1500
– DUMB a foolish or stupid person …1928 US sl.
– DUMB-ASS a foolish person …1958 US sl.
– DUMB-BELL a foolish person …1918 sl., orig. US
– DUMB BUNNY a foolish person …1921 sl., orig. US
– DUMB-BUTT a foolish person …1973 US sl.
– DUMB CLUCK a stupid oaf; a person as stupid as a chicken; a fool …1906 Aust. & US colloq.
– DUMB DORA a foolish woman or girl …1922 sl.
– DUMB-DUMB, DUM-DUM a foolish person …1937 sl., orig. Amer.
– DUMBFUCK a foolish person …1949 US sl.
– DUMBHEAD a foolish person …1887 sl., chiefly US
– DUMBKOPF a foolish person …1809 sl., orig. US
– DUMBO a dolt, a fool; a large and stupid oaf …1932 US sl.
– DUMBSHIT a foolish person …1961 US sl.
– DUM-DUM a foolish person …1937 sl., orig. Amer.
– DUMKOPF, DUMMKOPF a foolish person …1809 sl., orig. US
– DUMMOCK a fool, a blockhead …19C Eng. dial.
– DUMMY a foolish person …1796 sl.
– DUNCECOMB † a stupid person; a fool; a dim-witted person; a dunce …1612
– DUNDERHEAD (depreciative) a stupid, slow-witted person; an idiot; a fool …1630
– DUNDERPATE (depreciative) a stupid or foolish person …1697 arch.
– DUNDERWHELP (depreciative) a stupid or foolish person …a1625 arch.
– DWEEB a person held in contempt, esp. one ridiculed as studious, puny, or unfashionable; a fool …1982 US sl.
– ECHOHEAD a foolish person, usually female …1990s sl.
– EGG a foolish, ineffectual, or obnoxious person …1918 US sl.
– EGG-FOR-FUCK a fool, a simpleton, an obnoxious person …1990s US college sl.
– EGGHEAD a fool, a dolt, an idiot …1941 US sl.
– EGGNOG a foolish or obnoxious person …c1921 US sl.
– EGGO a fool, a misfit …1980s US college sl.
– ESEL, EZEL a fool, a simpleton …1910s S. Afr. sl.
– FART a fool, an unpleasant person, often older than the speaker …M18 sl.
– FART-ARSE a term of contempt; a fool; an incompetent …1940s sl.
– FARTHOLE a contemptible person ; an obnoxious or foolish person …1970 Amer. sl.
– FAT-BRAIN a fool, an idiot; often used affectionately as well as derogatorily …L16 sl.
– FAT-HEAD a fool, an idiot; often used affectionately as well as derogatorily …1842 sl.
– FEATHER-BRAIN a foolish, giddy person; a dull, stupid person; a silly, light-headed person …1839
– FILBERT a foolish, eccentric, or crazy person …1915 Amer. sl.
– FISH a person easily fooled; a fool, an oaf …20C US sl.
– FISH IN THE POOL a fool …1998 Brit. rhyming sl.
– FLAKE one who is ‘flaky’ or liable to act in an eccentric or crazy manner; also, a foolish, slow-witted or unreliable person …1968 sl.
– FLAT a fool; a soft-head …Bk1891 sl.
– FLAT-HEAD a foolish person …1862 sl.
– FLAT TIRE a fool, an oaf; a worthless man …E20 US sl.
– FLEAK (derogatory) a woman; a foolish or giddy woman …E17 Brit. colloq.
– FLURT an insignificant person; a fool …19C Eng. dial.
– FLY-FLAT a clever fool …1864 sl.
– FOOD FOR THE SQUIRRELS a stupid or foolish person …Bk1974 Amer. sl.
– FOO-FOO a fool, a worthless person …Bk1974 Amer. dial.
– FOOL KILLER a notional creature called upon to dispose of fools …1853 US sl.
– FOOL-FOOL a simple-minded fool …1994 Jamaica
– FOOLIO a fool; a social outcast …1994 US sl.
– FOOZLE a man who is easily humbugged; a fool …Bk1892 Amer. sl.
– FOPDOODLE † a silly, vain, empty person; a stupid or insignificant fellow; a fop, fool, simpleton …a1600
– FRIP a dull, foolish, or stupid person …1970 US college sl.
– FUCKWIT a foolish person …1969 sl., orig. Aust.
– FUNGE † a person lacking intelligence or common sense; a fool …1621
– FUTZ a foolish or unpleasant person …1935 US sl.
– FUTZER a foolish or unpleasant person …1938 US sl.
– FUZZBRAIN a foolish person …1969 US sl.
– GAABY a fool; a dolt …Bk1869 Eng. dial.
– GABBERLOONEY one who talks too much, acts the fool …Bk1997 Ireland sl.
– GABBY a stupid or foolish person; an idiot; a simpleton …1926 US sl.
– GABES a foolish person, one who acts foolishly; a busybody …Bk1900 Eng. dial.
– GABES-CHANY a foolish person, one who acts foolishly; a busybody …Bk1900 Eng. dial.
– GABEY, GABY – a stupid or foolish person; an idiot; a fool …1746 colloq. & Eng. dial.
– GABSHITE a fool; a dupe …1966 sl.
– GADAHA a fool, an idiot …1964 W. Indies
– GADGIE a fool, an idiot …1985 Sc. sl.
– GADSO a fool …17C sl.
– GAFONE (derogatory) an Italian; a fool …1976 sl.
– GAG a fool, a laughingstock …1840 US
– GAIBIE a stupid, foolish person; a blockhead, a simpleton, a fool, a lout …1790 Sc.
– GAISLING † a foolish, inexperienced person; a term of disparagement to a child …1819 Sc.
– GAKEM a stupid fellow; a fool …Bk1895 Eng. dial.
– GAKEY a left-handed person; an awkward, ungainly, clumsy person; a fool; a simpleton; a lout, a bumpkin …1726
– GALAH a foolish person …1938 Aust. sl.
– GALIMAVIS a fool, a stupid person …1925 Sc.
– GALLOOT, GALOOT a man, esp. if hulking, stupid, boorish, foolish, clumsy, or otherwise objectionable; an awkward or uncouth person …1818 UK
– GALLOWS-FOOL an arrant fool, one that deserves hanging …1894 Eng. dial.
– GAM a lout, a simpleton, a fool …1966 Irish sl. 
– GAMALEERIE a foolish, clumsy person; an old dotard …1880 Sc.
– GAMARAMUS † a fool, a nitwit …1849 Sc.
– GAMAREERIE, GAMMEREERIE a foolish, clumsy person …1880 Sc.
– GAMAWOW † a fool …1825 Sc.
– GAME  a person marked out to be cheated or fooled; a fool, a simpleton, esp. a victim …1699 criminals’ sl.
– GAMERAL, GAMMEREL a fool; a stupid fellow; a dunce; a silly lout …1826 Eng. dial.
– GAMERAMUS † a fool, a nitwit …1849 Sc.
– GAMF a buffoon, a fool; an empty-headed fellow who makes a great deal of noisy mirth; a fool, or one who wishes to seem so …1825 Sc.
– GAMFRAL, GAMFREL, GAMFRIL * a stupid or foolish person; a blockhead, an idiot; a forward, presumptuous person …1729 Sc.
– GAMFUL a fool, a buffoon …20C sl.
– GAMMERSTAGS a rude, wanton girl; an idle, loose girl; a foolish girl …1788 Eng. dial.
– GAMMERSTANG a rude, wanton girl; an idle, loose girl; a foolish girl …1788 Eng. dial.
– GAMMERSTEL a rude, wanton girl; an idle, loose girl; a foolish girl …1788 Sc.
– GAMMY a fool …1892 Aust. sl.
– GAMPH a fool, a buffoon; an empty fellow who makes a great deal of noisy mirth …1825
– GAMPHREL(L) a fool; a stupid or senseless fellow; a blockhead …1728 Sc.
– GANCH an awkward, silly fellow; a fool; a boor; an ignoramus; someone who behaves badly …Bk1880 N. Ireland
– GANDER a dull or stupid person; a fool, a simpleton; a gawky person …1553
– GANK a fool, an easy mark; a dupe …Bk2006 Amer. sl.
– GAPESNATCH a fool, a stupid person …Bk1868 Eng. dial.
– GAPIE a stupid, gaping, or irresponsible person; a fool …1908 Sc.
– GAPPER-MOUTH a fool; a simpleton …1886 Eng. dial.
– GAPPY a stupid, gaping, or irresponsible person; a fool …1908 Sc.
– GAPSHLY a simpleton, a fool …1896 Eng.dial.
– GAPUS a fool, a simpleton, a silly fellow; one who is noisily foolish …1825 Sc.
– GASOB a fool, a simpleton, a blunderer …1906 Aust. sl.
– GAUBSHITE an awkward, ill-kept, dirty person; a filthy, slovenly man; a boor, a fool, a blockhead …Bk1887 Eng. dial.
– GAUBY a simpleton, a fool, a dolt, a lout, an oaf  …Bk1869 Eng. dial.
– GAUCUM a fool, a simpleton, a booby; a stupid, clumsy fellow …1846 Eng. dial.
– GAUCUS a fool …1954 Sc.
– GAUK an awkward, clumsy person; a fool; a simpleton …1850 Sc. & Eng. dial.
– GAUKAMOUTH a gaping fool …Bk1886 Eng. dial.
– GAUKIE 1. an awkward, clumsy person; a fool; a simpleton; an idiot …1726 Sc.
2. a foolish, forward, vain woman …Bk1900 Sc.
– GAUKUM a fool, a simpleton, a booby; a stupid, clumsy fellow …1846 Eng. dial.
– GAUKY an awkward, stupid, badly-mannered person; an oaf; an awkward fool; a simpleton who stares vacantly ..Bk1828 Eng. dial.
– GAUM a painfully stupid or gullible person; a fool …1837 sl., orig. Irish
– GAUMBLIN a fool; a simpleton; a greenhorn …1840 Eng. dial.
– GAUMERIL a fool; a stupid fellow; a dunce; a silly lout …1826 Sc. & Eng. dial.
– GAUMLESS – stupid, half-witted person; a fool …1896 Eng. dial.
– GAUMLESS-HEAD a stupid, half-witted person; a fool …1896 Eng. dial.
– GAUMRIL a fool; a stupid fellow; a dunce; a silly lout …1826 Eng. dial.
– GAUMUCK a stupid person; a fool …1890 Eng. dial.
– GAUNCH an ignoramus; someone who behaves badly; a fool; a boor …1997 Ulster sl.
– GAUP a fool or simpleton, a stupid person; one who gapes rudely …1825 Sc. & Eng. dial. & colloq.
– GAUPIE a fool or simpleton, a stupid person; one who gapes rudely …1880 Sc.
– GAUPUS a stupid, silly person, a simpleton; a fool; a clumsy lout; an open-mouthed, vacant-minded person, esp. one given to talking much and foolishly …1808 Sc. & Eng. dial.
– GAUPY a vacant, staring person; a fool, a blockhead, a simpleton; a stupid or silly person …1856 Sc. & Eng. dial.
– GAUSTER a violent, unmanageable fellow; a swaggering fellow; a fool …1815 Sc. & Eng. dial.
– GAUVERIL an awkward, foolish fellow …Bk1900 Eng. dial.
– GAUV(E)Y a fool, a simpleton, a dunce; a half-witted person; a vacant-minded person, one that is easily imposed upon …1796 Eng. dial.
– GAUVISON an awkward, gaping fellow; a fool, a simpleton, a silly, staring fellow, a blockhead; a dunce; on easily imposed upon …1788 Eng. dial.
– GAVON (derogatory) an Italian; a fool …1976 sl.
– GAVONE (derogatory) an Italian; a fool …1968 sl.
– GAVYSON an awkward, gaping fellow; a fool, a simpleton, a blockhead; a dunce …1788 Eng. dial.
– GAWBY a stupid or foolish person; an idiot; a blockhead; a simpleton; a lout …1746 colloq. & Eng. dial.
– GAWCUM an awkward, ungainly, clumsy person; a fool; a simpleton …Bk1825 Eng. dial.
– GAWK an awkward, clumsy, stupid person; a fool; a simpleton; a lout, a bumpkin, an uncultivated person; a dupe …1685
– GAWK-A-MOUTH a gaping fool; one who stares vacantly …1777 Eng. dial.
– GAWKER a gaping fool; one who stares vacantly …Bk1900 Eng. dial.
– GAWKEY, GAWKIE, GAWKY a left-handed person; an awkward, ungainly, clumsy person; a foolish, gaping person; a simpleton; a lout, a bumpkin …1726
– GAWK-HAMMER a gaping fool; one who stares vacantly …1872 Eng. dial.
– GAWK-HEAD a foolish, awkward person …Bk1876 Eng. dial.
– GAWKUM a fool, a simpleton, a booby; a stupid, awkward, clumsy fellow; a lout …1846 Eng. dial.
– GAWKUMY a fool, a simpleton, a booby; a stupid, clumsy fellow; a lout …1846 Eng. dial.
– GAWKUS a fool …1954 Sc.
– GAWM a painfully stupid or gullible person; a fool; a simpleton; a lout …1837 sl., orig. Irish
– GAWMBLIN a fool; a simpleton; a silly fellow; a greenhorn …1840 Eng. dial.
– GAWMEREL a fool; a stupid fellow; a dunce; a silly lout …1826 Eng. dial.
– GAWMOGE a painfully stupid or gullible person; a fool …Bk1910 Ireland English
– GAWN(E)Y a fool; a simpleton; a stupid, awkward person …1777 Eng. dial. 
– GAWNICUS a fool, a dolt, a stupid fellow, an ignoramus, a simpleton …1867 Amer. dial.
– GAWP a fool or simpleton, a stupid person; one who gapes rudely …1825 Sc. & Eng. dial.
– GAWPIE a fool or simpleton, a stupid or silly person; one who gapes rudely; one who laughs without reason …1825 Sc.
– GAWPSHEET an awkward, ill-kept, dirty person; a fool, a blockhead …Bk1887 Eng. dial.
– GAWPUS a stupid, silly person, a simpleton; a fool; a blockhead; a clumsy lout; an open-mouthed, vacant-minded, staring person, esp. one given to talking much and foolishly …1808 Sc. & Eng. dial.
– GAWVISON a silly, awkward, gaping fellow; a noisy, foolish person; a simpleton, a blockhead; a half-witted person; a dunce …1788 Eng. dial.
– GAWVY a fool, a simpleton; a half-witted person; an open-mouthed fellow …Bk1877 Eng. dial.
– GAZAYBEE a fool …1983 Irish sl.
– GAZEBO a fool …1983 Irish sl.
– GAZINK a  fool …1922 US sl.
– GAZOB a foolish person …1906 Aust. sl.
– GAZOO a fool; a stupid or unpleasant person; a lout, a boor …1914 UK sl.
– GAZOOB a fool, a simpleton, a blunderer …1906 Aust. sl.
– GAZOOK a fool; a stupid or unpleasant person; a loud lout, a boor; a clumsy oaf; an ineffectual or incompetent person …1901 US sl.
– GAZOOKUS a fool; a stupid or unpleasant person; a lout, a boor …1924 US sl.
– GAZOONEY, GAZOONIE, GAZOONY – a boy or lad; an inexperienced youth; a foolish, ignorant or eccentric fellow; a naive person …1914 US sl.
– GAZOOP a fool; a stupid or unpleasant person; a lout, a boor …1901 US sl.
– GAZOOPUS a fool; a stupid or unpleasant person; a lout, a boor …1933 US sl.
– GAZUNY an amusing person; a fool …1917 US sl.
– G.D.F. a God-Damned Fool …1917 US sl.
– GECK  a fool, a simpleton, a dunce; a stupid, clumsy fellow; one who is befooled or derided, one easily imposed on, a dupe …c1530 obs. exc. Eng. dial.
– GEEK a person, a fellow, esp. one who is regarded as foolish, offensive, worthless, etc.; a clumsy or eccentric person; one who is befooled or derided; a dupe …1876 sl., orig. N. Eng. dial.
– GEEK-A-MO a geek; a fool …1991 US surfing sl.
– GEIT a foolish fellow, an idiot; a madman …Bk1900 Sc.
– GEKE † a fool, a simpleton; one who is befooled or derided, a dupe …1515 obs. exc. Eng. dial.
– GELLYHEAD a fool …1992 NZ sl.
– GERBIL a stupid, insignificant, or unpleasant person; a foolish or obnoxious person …1986 US sl.
– GET(T), GHET an idiot; a fool; an unpleasant or despicable person; a term of abuse …1931 UK sl.
– GETSIE an idiot; a fool; an unpleasant person; a term of abuse …1935 UK sl.
– GEUP a foolish person …1950 Sc.
– GHOMEY a painfully stupid or gullible person; a fool …1837 sl., orig. Irish
– GIBLET a stupid, foolish, or inept person …1984 US sl.
– GIBONEY a stupid, foolish, or offensive person; also, a hired thug, a hoodlum; broadly, a man, a fellow …1921 Italian-American sl.
– GIDDY GERTIE a foolish female …Bk1945 jive usage
– GIDDY GOAT an irresponsible fool …Bk1958 Eng. sl.
– GIG a fool, a simpleton, an idiot, a stupid person; a trifling, silly, flighty fellow …1685 Eng. dial.
– GIG APE a fool; an idiot …1948 Aust. sl.
– GIGHEAD a fool, an idiot …1940s Aust. sl.
– GILL a gullible or credulous person; a fool …1592
– GILLIE, GILLY a rather stupid, foolish or silly person; a simpleton …1770
– GILLIEGACUS, GILLIGACUS, GILLY-GACUS * a foolish or silly person; a simpleton …1719 Sc.
– GILLIEGAPUS, GILLY-GAPUS * a foolish or silly person; a simpleton; a person who is lanky, awkward, or stares stupidly …1719 Sc.
– GILLIEGAUKIE, GILLIE-GAWKIE, GILLY-GAUKIE, GILLY-GAWKIE * a foolish or silly person; a simpleton; a person who is lanky, awkward, or stares stupidly …1719 Sc.
– GILLIEPEROUS  a stupid fool …1935 Sc.
– GILLY-GAUPIE, GILLY-GAWPIE, GILLY-GAWPY – * a foolish or silly person; a simpleton; a person who is lanky, awkward, or stares stupidly …1719 Sc.
– GILLY-GAUPUS, GILLY-GAWPUS – * a foolish, silly, or half-witted person; a simpleton; a person who is lanky, awkward, or stares stupidly …1719 Sc.
– GILLY-GAWKER – * a foolish or silly person; a simpleton; a person who is lanky, awkward, or stares stupidly …1719 Sc.
– GILLY-GAWPOCK – * a foolish or silly person; a simpleton; a person who is lanky, awkward, or stares stupidly …1719 Sc.
– GIMMICK a foolish, peculiar, or eccentric person; one who has been mulcted by cults, healers, fortune-tellers, or mystics …1926 US sl.
– GIMP (derogatory) a stupid, foolish, unpleasant, obnoxious, or contemptible person; a simpleton; an incompetent or weak person …1924 sl., orig. US
– GIMPY (derogatory) a stupid, foolish, unpleasant, obnoxious, or contemptible person …1959 US sl.
– GINK (often derogatory) a fellow; a guy; esp. an odd, eccentric, or foolish man; a stupid or useless person; someone who is unworldly or socially inept …1906 sl., orig. US
– GIPE, GYPE a fool, an idiot …1825 Sc.
– GIT a fool, an idiot, a dolt; a worthless person, a good-for-nothing …1858
– GITE a foolish fellow, an idiot; a madman …Bk1900 Sc.
– GIZMO a foolish or inconsequential man …1942 US sl., esp. Navy usage
– GLADDIE a fool …1892 Eng. dial.
– GLAVER one who is addicted to idle, foolish gossip; an idle, foolish person …1825 Sc. & Eng. dial.
– GLEEP an odd, obnoxious, or foolish person; a stupid person; an oaf; a disliked person …1947 US college sl.
– GLOCK a fool; a half-witted person; an eccentric person …1886 UK sl.
– GLOFFUS a rough, uncouth person of noisy, foolish, or light-headed behaviour, often referring to one of ugly or unprepossessing appearance …1866 Sc.
– GLOIK a fool, a simpleton; applied to a woman …1950 Aust. sl.
– GLOIT a fool, a simpleton; applied to a woman …2005 Aust. sl.
– GLOM a fool, a stupid person; an awkward person; a worthless or inept person; a dunce …1930 US sl.
– GLOP a fool …1864 Eng. dial.
– GLOWT a fool, a blockhead; a clumsy fellow …Bk1878 Eng. dial.
– GLOW-WORM a term of contempt; a foolish person …1624
– GLUEHEAD a fool …1839 UK sl.
– GLUFFIS, GLUFFUS a rough, uncouth person of noisy, foolish, or light-headed behaviour, often referring to one of ugly or unprepossessing appearance …1866 Sc.
– GLUMF a sulky fool …Bk1876 Sc.
– GLUNDIE, GLUNDY  an inactive, awkward, or clownish person; a fool; a stupid person …1824 Sc.
– GLUNNY  an inactive person; a fool; a stupid person …1825 Sc.
– GLYORACH a fool; a blockhead …1936 Sc.
– GNAW-POST a stupid, ignorant person; a silly fellow; a fool, a simpleton …1856 Eng. dial.
– GO-ALONG a fool; a soft-head …Bk1891 sl.
– GOAT a foolish person …1916 sl.
– GOBALOON one who talks too much, acts the fool …20C Ireland sl.
– GOBBERLOONY one who talks too much, acts the fool …20C Ireland sl.
– GOBDAW a foolish person …a1966 Anglo-Irish
– GOKY †* a fool, a simpleton …1377
– GOM a foolish, awkward person; a simpleton; an idiot …1996 Ireland
– GOMF a buffoon, a fool; an empty-headed fellow who makes a great deal of noisy mirth; a fool, or one who wishes to seem so …1825 Sc.
– GONEY a stupid, awkward person; a foolish fellow; a simpleton …1838 Amer. dial.
– GONK a fool; an idiot …2003 UK teen sl.
– GONNER-HEAD a fool; a stupid fellow, a dunce …1740 Eng. dial.
– GONNER-PATE a fool; a stupid fellow; a dunce …Bk1900 Eng. dial.
– GONUS a fool, a dolt, a stupid fellow, an ignoramus, a simpleton …1842 Amer. dial.
– GONY a stupid, awkward person; a foolish fellow; a simpleton …1859 Amer. dial.
– GONZO a foolish person …1977 sl., orig. & chiefly US
– GOOBER an idiot, a fool; an incompetent, a country bumpkin …M19 sl.
– GOOBY a stupid, foolish person; a blockhead, a simpleton, a fool, a lout …1790 Eng. dial.
– GOOF an oaf, a ridiculous jerk; an incompetent fool …1916 US sl. & colloq.
– GOOF-BALL a jerk; an oaf; an incompetent fool …1944 US sl.
– GOOFER an oaf, a ridiculous jerk; an incompetent fool …20C US sl. & colloq.
– GOOFIE a fool …1920s US campus sl.
– GOOFUS an oaf, a ridiculous jerk; an incompetent fool …1917 US sl. & colloq.
– GOOFY a fool …1920s US campus sl.
– GOOG a fool …1910s sl.
– GOOGIE, GOOGY a fool …1910s sl.
– GOO-GOO a silly fool …1910s US sl.
– GOOK a dull, stupid, foolish person …1910s sl., orig. US
– GOON a stupid, awkward person; a foolish fellow; a simpleton …1921 sl., orig. US
– GOONEY a foolish or stupid fellow; a simpleton …1815 Eng. & Amer. dial.
– GOONUS a fool, a dolt, a stupid fellow, an ignoramus, a simpleton …1959 Amer. dial.
– GOONY a stupid, awkward person; a foolish fellow; a simpleton …1948 Amer. dial.
– GOOP a foolish person …1900 sl., orig. US
– GOOSECAP † a silly fellow; a stupid, foolish person; a simpleton; an idiot; a giddy or flighty young girl …1589 obs. exc. Eng. dial.
​- GOOSTRUMNOODLE a stupid person; a fool …1871 Eng. dial.
– GORBY a stupid, foolish person; a blockhead, a simpleton, a fool, a lout …1790 Eng. dial.
– GORM a foolish person …1912 sl.
– GOUK a dull, stupid, foolish person …1910s sl., orig. US
– GOZZARD a fool, a simpleton …B1900 Eng. dial.
– GRAMPUS a blusterer; a blustering fool …1823 US sl., esp. nautical usage
– GREENLANDER a fool; a soft-head …Bk1891 sl.
– GRIZZLEDEMUNDY a term of abuse applied to a person who laughs at any trifling thing; a grinning fool; a stupid oaf …1818 Eng. dial.
– GROLL † a foolish or superficial person; a gossip, a smatterer …1637
– GUBBINS a foolish person …1916 Brit. sl.
– GUCK † a foolish saying; a fool …1596 Sc.
– GULL-FINCH † a fool, a simpleton; a person easily deceived …1630
– GULPIN one who will swallow anything; one easily gulled; a credulous simpleton; a fool …1802
– GUMP a foolish person …1722 sl., now US
– GUMPH a foolish person …1722 sl., now US
– GUMP-HEAD a stupid, foolish, or awkward person; an idiot; a senseless person; a dolt …1916 Amer. dial.
– GUMPUS a foolish person; a dolt …1825 Sc.
– GUMPY a stupid, foolish, or awkward person; an idiot; a senseless person; a dolt …1892 Amer. dial.
– GUM-SUCKER a fool, a simpleton …1936 Aust.
– GUP a fool …c1925 Aust. sl.
– GUPPY a fool …c1925 Aust. sl.
– GUY a person who is an object of ridicule or derision; broadly, a fool …1823 Amer. sl.
– HABERMAGULLION a fool; a useless person …Bk1997 Ulster sl. 
– HAIR-BRAIN  one who has a brain like a hare’s, or no more brain than a hare; a giddy or reckless person; an oaf; a fool …1550
– HAIRPIN a fool, a simpleton …1876 US sl.
– HAIVERALL, HAIVEREL, HAIVREL a person given to foolish or inconsequential chatter or gossip; also, a stupid or ignorant person, a fool, a simpleton …1772 Sc.
– HAL a fool, a jester; a silly person …1857 Eng. dial.
– HALF-BAKE a fool, an inadequate person …1943 UK sl.
– HALF-BAKED a half-baked person; a foolish, silly, or half-witted person; an immature person …1866 colloq. & Eng. dial.
– HALF-CHAR a foolish fellow …Bk1905 Eng. dial.
– HALF-IDIOT a complete fool …1990 W. Indies sl.
– HALFLIN(G) a half-witted person; a fool …1808 Sc. & Eng. dial.
– HALF-NATURAL a fool …Bk1880 Eng. dial.
– HALF-ROCK a foolish or half-witted fellow …1893 Eng. dial.
– HALF-THICK a foolish fellow …1896 Eng. dial.
– HALF-WIT a foolish person …1755 sl. 
– HALFY a fool; a half-witted person …Bk1905 Eng. dial.
– HALIBUT a foolish or offensive person …1905 US sl.
– HALLACKING a foolish person …1841 Eng. dial.
– HALLIKIN a foolish person …Bk1877 Eng. dial.
– HALLOCKIT a noisy, restless person; a romp, a hoyden; a fool, a good-for-nothing, a worthless person …1787 Sc.
– HAMBURGERHEAD a stupid or worthless person; a fool; one who has no more brains than a hamburger …1955 US sl.
– HAMHEAD a fool, a stupid or worthless person …1927 US sl.
– HAMPTON (WICK) a fool …1989 UK rhyming sl. for ‘prick’
– HANDLE a fool …1835 UK sl.
– HANKTELO a silly fellow; a fool; a simpleton …1593 UK sl.
– HANS WURST a fool, an idiot …1869 US sl.
– HA’P’ORTH a ‘halfpennyworth’; a fool …1974 UK sl.
– HARDHEAD an unthinking or unintelligent person; a blockhead; a fool; a stupid person; also, a person who is stubborn and uncompromising …1576
– HARE-BRAIN † one who has a brain like a hare’s, or no more brain than a hare; a giddy, reckless or rash person; an oaf, a fool …1550
– HARRY HUGGINS a fool, an idiot …1992 UK rhyming sl. for ‘muggins’
– HASH one who talks nonsense; a fool; a scamp; also, a term of endearment for a boy …1685 Sc. & Eng. dial.
– HAUM-GOBBARD a silly, clownish fellow; a foolish person …1790 Eng. dial. 
– HAVERAL-HASH a silly, nonsensical person; a fool …1870 Sc.
– HAVEREL, HAVERIL, HAVREL a foolishly chattering or garrulous person; one given to inconsequential chatter or gossip; a fool; a stupid, half-witted, or ignorant person; a simpleton …1772 Sc. 
– HAWBUCK an ungainly or clumsy person; an unmannerly lout; a country bumpkin or clown; a rude, ignorant rustic; a coarse, vulgar lad; a foolish or stupid fellow; a simpleton; a noisy, rough, turbulent young man …1787
– HAWFLIN a half-witted person; a fool …1808 Sc. & Eng. dial.
– HAWG a ‘hog’; a miser, a mean person; a foolish person …1940 US sl.
– HAZE-BAZE a fool, a stupid person, a ninny …1877 Ireland
– HEAD JOB a fool …2003 NZ sl.
– HEAD-THE-BALL a foolish or silly person; an idiot; also, a crazy person, esp. one who is violent or unpredictable …1958 colloq., chiefly Irish & Sc.
– HEARTH-RUG a fool; a simpleton …1998 Brit. rhyming sl. for ‘mug’
– HEATHER-GOOSE a dolt, a fool, a ninny …c1870 Sc.
– HEEPY † a fool, a stupid person …1800 Sc.
– HELIUM-BRAIN a silly or empty-headed person; a fool; an airhead …1978 US college sl.
– HELIUM HEAD a silly or empty-headed person; a fool; an airhead …1960 US college sl.
– HELLICAT * a bad, worthless, or foolish person; a wicked or cruel person; a villain …1816 orig. & chiefly Sc.
– HERBERT a stupid, foolish, ridiculous, or inconsequential person …1960 Brit. sl.
– HERKIMER JERKIMER a rustic, a fool, a screwball …1946 Amer. sl.
– HERRING a worthless, foolish, offensive, or inconsequential person …1575 sl.
– HICHCOCK  a term of contempt; a simpleton; a fool …1607
– HICK JOP a country bumpkin; a fool …1809 sl.
– HOBALL † a clown, a fool, a dolt, an idiot …a1553
– HOBBIL, HOBBLE a fool, a dull, stupid person; a blockhead, a dunce, an idiot …1740 Sc. & Eng. dial.
– HOBBY HORSE a fool, a jester …L16 sl.
– HOB-GOB a fool, an idiot; an awkward, uncouth person …B1900 Eng. dial.
– HODDY-DODDY † a foolish or ridiculous person; a simpleton; a dupe …1646
– HODDY-NODDY †* a fool, simpleton, noodle …1600
– HODDYPEAK † a fool, a simpleton, a blockhead …1500
– HORSE MARINE a lubberly or clumsy fool; a dolt …1823 US nautical & military usage
– HORSE’S ASS a fool …Bk1995 US sl.
– ICK a fool, a gullible or easily deceived person …1930s US Black sl.
– ICKAROO a fool, a gullible or easily deceived person …1930s US Black sl.
– IDIOT a term of reprobation for one who speaks or acts in what the speaker considers an irrational way, or with extreme stupidity or folly; a blockhead; a stupid person; an utter fool; a crazy person …c1375
– IDYAT BWAI a fool …1997 W. Indian patois (idiot boy) 
– IG MAN an ignorant man; a fool …20C US Black sl.
– IGNARO † one that is ignorant; a fool, a blockhead, a dunce, an ignoramus …1620
– IGNO a fool …1970s US sl.
– IGNUTS an ignorant fool …1934 US sl.
– IMBO a simpleton, a fool; an imbecile; a gullible person, esp. the victim of a criminal …1953 Aust. sl.
– IMBY a fool, a simpleton …1980s US sl. 
– IMPLEMENT a fool easily engaged in any enterprise, though difficult or dangerous …1690 sl.
– INCOMPOOT a nincompoop, a fool, a silly person, a trifler …Bk1902 Eng. dial.
– INSIPIENT † an unwise, foolish or silly person …1494
– IRONHEAD a stupid oaf, a fool …20C sl.
– ISRAEL a fool, an idiot …Bk1902 Eng. dial.
– IT-SHAY an oaf or a fool …20C US Pig Latin for ‘shit’
– IVORY DOME a stupid person; a fool …1911 US sl.
– J a fool, an oaf …19C Brit. sl.
– JACK a fool …1548
– JACK-ADAMS a foolish and stubborn person; a simpleton; a silly, impertinent fellow …1690 sl.
– JACKALALLY a foolish person …Bk1893 Eng. dial.
– JACK AND JILL. a fool …1973 Aust. rhyming sl. for ‘dill’
– JACK-A-NODS a simple, stupid fellow; a fool; a simpleton…Bk1852 Eng. dial. 
– JACKASS a foolish or stupid person; an idiot, a dolt …1756
– JACK-FOOL a great fool …1383 sl.
– JACK LANTERN a fool; a dull, stupid fellow …1896 Amer. dial.
– JACOB † a simpleton; a fool; a half-witted fellow; an oaf …1785 sl.
– JARHEAD (derogatory) a dull, stupid person; a fool, an oaf …1969 Amer. dial.
– JAZZBO a clumsy, clownish or foolish person; an oaf; a rude or annoying person …1923 Amer. sl.
– JEEP a foolish, inexperienced, or offensive individual …1938 Amer. sl.
– JENNYASS a female fool …1940 Amer. dial.
– JERK an oaf or incompetent fool …1935 US sl.
– JIMCRACK a fool, an idiot, a half-witted person …1908 Amer. dial.
– JOBARD † a stupid fellow; a fool …a1400
– JOBBERNOWL a stupid, thick-headed person; a blockhead, a fool, a dunce, a dolt …1592 colloq.
– JOE ERK a fool; an oaf; a jerk; a wretched man …World Wars rhyming sl. for ‘jerk’ and ‘berk’
– JOE HUNT a fool; an oaf; a jerk; a wretched man …20C Brit. rhyming sl. for ‘cunt’
– JOLTERHEAD a fool; a stupid person …L18 sl.
– JOLTHEAD a fool; a stupid person …L18 sl.
– JUGGINS a dolt; a fool; a soft-head; gullible person; a dupe …1682
– KANG † a fool …a1225
– KIME †* a simpleton, a fool, a silly fellow…c1305
– KLUCK a stupid oaf; a fool …20C US colloq.
– KNOCK-SOFTLY a silly or stupid person; a fool …1887 Eng. dial.
– KNOW-NOTHING one who knows nothing; an ignorant person; a fool …1839
– LABBET a fool …Bk1902 Eng. dial.
– LABRICK a fool; a dolt; an idiot; a dull, stupid person; a greenhorn; a stranger; a naive or foolish person; often used as a mild term of abuse …1889 Amer. sl.
– LACK-BRAIN one who is destitute of sense or brains; one wanting in wit; a stupid, empty-headed fellow, a fool …1596
– LALDRUM a simpleton; a complete fool …Bk1902 Eng. dial.
– LAMB a simpleton, a fool, esp. one easily cheated of their money …1668
– LAME a person who is ‘lame’; a fool, an idiot; an unsophisticated person; one who does not fir in with a particular social group  …1958 US sl., chiefly Black usage
– LAMEBRAIN a fool, an idiot …1919 US sl.
– LAME-O a fool; an idiot; an unsophisticated person …1977 US college sl.
– LAMER a person who is ‘lame’; a fool, an idiot; an unsophisticated person …1961 US sl.
– LAMESTER a foolish or contemptible person …1978 US sl.
– LANE a person easily imposed upon or cheated; a victim; also, one who is foolish or socially unsophisticated …1933 US sl., esp. Black & criminals’ usage
– LARRY a fool …20C Irish sl.
– LAVERICK a fool; a dolt; an idiot; a dull, stupid person; a greenhorn; a naive person; a stranger; often used as a mild term of abuse …1895 Amer. dial.
– LEATHER-EARS a stupid person; a fool; one slow of comprehension …1903 Amer. dial.
– LEATHER-HEAD a fool, a blockhead, a dolt, an oaf, a stupid person; a person slow of comprehension …a1700
– LEATHER-NECK a stupid person; a fool; a blockhead; an uncouth person …1919 Amer. dial.
– LEMON a victim; a fool …1908 sl.
– LIGHTS a fool; a soft-head; an oaf …1682 Brit. colloq.
– LINTBRAIN a foolish, dim-witted, or ignorant person …1990 US sl.
– LINTHEAD a foolish, dim-witted, or ignorant person …1960 US sl.
– LOB-COAT † a country bumpkin; a clown, a lout, a boor; a heavy, dull person; a blundering fool …1604
– LOBCOCK † a country bumpkin; a clown, a lout, a boor; a dull, stupid, sluggish person; a clumsy, lubberly fellow; a blundering fool; a blockhead; a term of abuse …a1553 obs. exc. Eng. dial.
– LOGGERHEAD a fool; a dullard …L16 sl.
– LOMMIX a large, heavy, or clumsy person; an ungainly or stupid lout; a fool …M19 sl.
– LOOB a fool, a dullard …M14 Eng. dial.
– LOOBY a fool; a soft-head …Bk1891 sl.
– LOOGAN a foolish person …1929 US sl.
– LOONY a fool; a soft-head …Bk1891 sl.
– LOOP a fool …1940s Aust. sl.
– LOX a fool; a lummox …1966 Amer. sl.
– LOX-FOR-BRAINS a fool …1977 Amer. sl.
– LUB a fool …M14 sl.
– LUBBER a fool; a soft-head …M14 sl.
– LUMMIX, LUMMOCK(S), LUMMOX, LUMMUX a large, heavy, or clumsy person; an ungainly or stupid lout; a fool …M19 sl.
– LUMMOKIN a large, heavy, or clumsy person; an ungainly or stupid lout; a fool …M19 sl.
– LUNATIC a madly foolish person …1602
– LUNCH a dull, stupid person; a fool …1960s US college sl.
– LUNCHBAG a dull, foolish person; an undesirable person …1950s US college sl.
– LUNCHBOX a dull, foolish person; an undesirable person …1950s US college sl.
– LUNCHBUCKET a dull, foolish person; an undesirable person …1950s US college sl.
– LUNCHIE a dull, stupid person; a fool …1960s US college sl.
– LUNCHPAIL a dull, foolish person; an undesirable person …1950s US college sl.
– LUNCHSACK a dull, foolish person; an undesirable person …1950s US college sl.
– LUNK a fool …M19 US sl.
– LUNKHEAD an absolute fool; an idiot; an incompetent …M19 sl., orig. US
– LUSH a victim or fool …1940s US sl.
– MACARONI a merry fool, esp. if an Italian …1711 colloq.
– MACAROON  a buffoon; a stupid or foolish person; an affected blockhead; a ridiculous or doltish person …a1631 
– MACKEREL (AND SPRAT) a worthless, stupid or foolish fellow …1863 Brit. rhyming sl. for ‘prat’
– MACKY-MOON a fool, a silly person; one who makes himself absurd or ridiculous by playing the fool; a queer-looking figure …1872 Eng. dial.
– MACO a fool, an idiot …20C W. Indies sl.
– MADDLIN(G) a fool, simpleton, blockhead …Bk1905 Eng. dial.
– MAD HADDOCK a very eccentric, crazy, or foolish person …20C Aust. sl.
– MADLING a mad creature; one who acts wildly or foolishly …c1648-50
– MADPASH † a foolish or insane person; a lunatic, a mad fellow; a crackbrained person; a scatterbrain; a hot-headed person; a rash or turbulent person; a wild, giddy person …1611 
​- MAFF a fool; a foolish, silly person …Bk1905 Eng, dial.
– MAFFLARD † a stammering or blundering fool; a term of contempt …c1450
– MAFFLIN a simpleton; a silly, foolish person …Bk1905 Eng, dial.
– MAGHNOON a fool; a dolt; an idiot …L19 among troops in Egypt
– MAGOO a useless or foolish person; an absent-minded or inattentive person …1932 Amer. sl.
– MAGUFFIN a foolish, blundering person, an oaf …1832 Sc.
– MAISLIN a fool, a simpleton, an idiot …1781 Eng. dial.
– MAISLYKIN a fool, a simpleton, an idiot …1781 Eng. dial.
– MAKIN a fool, a simpleton …Bk1905 Eng. dial.
– MAKO a fool, an idiot …20C W. Indies sl.
– MALLETHEAD a fool, a stupid person, a numbskull …1954 US sl.
– MAMELT, MAMMELT a simpleton, a fool …1790 Eng. dial.
– MAMMY-GOG a foolish, stupid person …1884 Eng. dial.
– MAMMY-SUCK a foolish, stupid person …Bk1905 Eng. dial.
– MAN IN THE MOON a fool, an eccentric or crazy person …20C rhyming sl. for ‘loon’
– MANMANPOUL a gullible fool …20C W. Indies sl.
– MARLOCK one who plays pranks; a fool …1790 Eng. dial.
– MAROON an obnoxious or foolish person; a stupid person  …1941 Amer. sl.
– MATHUM a fool, a stupid person; a blockhead …Bk1905 Eng. dial.
– MAWKS a foolish, slatternly woman; an overgrown, clumsy girl …1721 Eng. dial.
– MAY-GAME a foolish, silly person …1886 Eng. dial.
– MAZED-ANTIC a wild, foolish, crazy person …Bk1905 Eng. dial.
– MAZICAN a stupid person; a fool …Bk1905 Eng. dial.
– MAZLEKIN a fool, a simpleton, an idiot …1781 Eng. dial.
– MAZLIN a fool, a simpleton, an idiot …1781 Eng. dial.
– MAZY-JACK a fool, an idiot; a parish fool …1876 Eng. dial.
– MCFLY a fool; an empty-headed person …1980s US campus sl.
– MEATHUM a fool, a stupid person; a blockhead …Bk1905 Eng. dial.
– MEE-MAW a simpleton, a fool …1895 Eng. dial.
– MENTAL GIANT a fool, an idiot …1980s US campus sl.
– MENTAL HERNIA a fool; an idiot; an oaf; a stupid person …1970 Amer. sl.
– MESS an objectionable or foolish person; unruly or incorrigible person; an oaf; a hopelessly stupid person; a mentally confused person …1936 sl.
– MICKEY MOUSE a small, timid, inconsequential, or foolish person …1941 
– MOAK, MOKE a stupid fellow, a dolt, a blockhead; a foolish or inconsequential fellow …1855 Eng. dial. & sl.
– MOBARD, MOBBARD †* a villain, a rascal; a fool; a clown, a boor …a1450
– MOBY DICK a fool, an idiot …Bk2004 Brit. rhyming sl. for ‘prick’
– MOEGIE, MOEGOE, MOGGOE, MOGO – (derogatory) a country bumpkin; a rustic; a dull, foolish, or gullible person; a person who fails to fit in, a misfit; a lazy lout …1953 S. Afr. colloq.
– MOISEY, MOISY – a person of soft intellect, an idiot, a fool …Bk1905 Eng. dial.
– MOKE a person who is stupid, awkward, or incompetent; a dolt, a fool …1855 colloq.
– MOKES a foolish or inconsequential fellow; a stupid fellow …1985 Amer. sl.
– MOLLY a fool …1905 US sl.
– MOLLY-BOOBY a foolish person …1965 Barbados sl.
– MOLLYHAWK a fool, a simpleton, an idiot …1900 sl.
– MOLLYHEAD a fool; a simpleton; an idiot  …1902 sl.
– MOME †* a fool, a stupid or silly person; a blockhead, a simpleton; a dull, ignorant person; a dolt …1550
– MOMPARA an incompetent person; a fool; an idiot; also used affectionately, and as a form of address …1930 S. Afr. colloq.
– MONAGHAN  a clown, a fool …1689 Ireland colloq.
– MONG (offensive) an idiot; a fool; a mentally slow or backward person …1980 Brit. colloq.
– MONGY (offensive) an idiot; a fool; a mentally slow or backward person …2000 Brit. colloq.
– MONIMENT a ridiculous or objectionable person; a laughingstock, a fool, a rogue …1866 Sc.
– MONKEY a child; a junior; a foolish person …1583
– MONUMENT a ridiculous or objectionable person; a laughingstock, a fool, a rogue …1866 Sc.
– MOO (humorous or derogatory) a person regarded as misguided, foolish, or incompetent, usually a woman …Bk1909
– MOOFUS a fool …1920 US sl.
– MOOJIN a fool, a simpleton …1996 W. Indies
– MOOK (derogatory) a term of abuse; an incompetent, ineffectual, foolish, or stupid person; a contemptible person (esp. with reference to low social status) …1930 US & Caribbean colloq.
– MOO-MOO a fool, a simpleton …1973 W. Indies sl.
– MOONCALF a born fool; a congenital idiot; a simpleton …1627 colloq.
– MOONEY a fool; a soft-head …Bk1891 sl.
– MOON-HEAD a silly, awkward fellow; an oaf; a fool …1919 Amer. dial. 
– MOONLING † * a simpleton, a fool, an idiot, a silly fellow, a lunatic …1631
– MOONRAKER a very foolish or silly person; a blockhead …c1840 Brit. colloq.
– MOONY a fool; a silly fellow; a simpleton; a soft-head …1682 sl.
– MOOSIE, MOOSY, MOOZY a person of soft intellect, an idiot, a fool, a blockhead, a stupid person …Bk1905 Eng. dial.
– MOP  a fool, a simpleton, an oaf …c1330
– MOPE a fool, a stupid person, a simpleton; a dolt, an oaf; a dullard; a slow-witted or inept person …c1390
– MOPEY a fool; used as a term of derogatory address …1920s sl.
– MOPOKE a stupid, ineffectual, or tiresome person; a slow or lugubrious person; a fool; often used as a term of abuse …1845 chiefly Aust.
– MOP-STICK †* a stupid person; a fool; an idiot …1882 sl.
– MORBAN a silly, foolish person …Bk1879 Eng. dial.
– MOREPORK a stupid or tiresome person; a fool; often used as a term of abuse …1845 Aust. colloq.
– MOREPORK KIND OF A FELLOW a stupid or tiresome person; a fool …1845 Aust. colloq.
– MOROLOGIST †* a person who talks foolishly; a prating, foolish fellow …1727
– MORON a stupid or slow-witted person; a fool; an idiot; a feeble-minded person; a dunce …1917 colloq., orig. US
– MOROSOPH * a wise fool, a jester …1693
– MOS(E)Y – a person of soft intellect; an idiot, a fool …1824 Sc.& Eng. dial. 
– MOTHBALL * an insignificant or foolish person; an obnoxious or aggravating person; a teenage jerk; an irritating person; an over-diligent student …1944 US sl.
– MOTLEY  a fool, a jester in motley garments…a1605
– MOTLEY FOOL a professional fool …a1616
– MOTORHEAD a fool …1973 US sl.
– MOUSEBRAIN a fool, a birdbrain …1914 Amer. sl.
– MOUTH a person who talks foolishly; a slow-witted or gullible person; a fool; a dupe …1663 orig. cant
– MOUTH-BREATHER a stupid person; a fool …1915 Amer. sl.
– MOUZY a person of soft intellect, an idiot, a fool …Bk1905 Eng. dial.
– MOZEY, MOZIE, MOZY a person of soft intellect; an idiot, a fool …1824 Eng. dial.
– MR. NAWPOST a foolish fellow …c1696 sl.
– MUD a fool; an oaf; a stupid person …18C Brit. colloq.
– MUDDING-FACE a fool; a weakling …L19 sl.
– MUDDLE-HEAD a fool; a simpleton; a stupid person; an oaf  …M19
– MUD-HEAD an oaf; a fool; a stupid person …E19 colloq.
– MUFF an oaf, a fool, a stupid person …1682 cant
– MUFFIN a fool …1830 Brit. sl.
– MUFFIN-CAP a fool …M19 sl.
– MUG a stupid or incompetent person; a fool or simpleton; a gullible person, a dupe …1857 colloq.
– MUGGINS a foolish person …1855 sl.
– MUGGY-CUNT a fool …2000 UK sl.
– MUG LAIR a showy but foolish person …1944 Aust. sl.
– MULLETHEAD a fool, a stupid person …1857 US sl.
– MULLOCK (derogatory) a worthless or foolish person …1890 Aust. & NZ sl.
– MUMMYDIDDLE a stupid, silly person; a foolish person …Bk1903 Eng. dial.
– MUMMYHEAD a fool …1990s US Black gang usage
– MUSH a fool …20C US sl.
– MUSH-FACE a fool; a sentimental idiot …1920s sl.
– MUTANT a clumsy, foolish, or otherwise unpopular individual; generally used by adolescents …sl.
– NABALL a fool …1612 sl.
– NAF a fool; a weakling; an ineffectual person …1960s S. Afr. sl.
– NAILHEAD a dull, stupid person; a fool …1948 Amer. sl.
– NANA a foolish person …1941 sl., orig. Aust.
– NANNICOCK †* a silly, affected person; a young woman, as a term of contempt; also, a fool …1600
– NANNY-CRATTY an inquisitive, meddlesome, foolish, weak-minded person …Bk1905 Eng. dial.
– NANNY-GOAT a foolish girl or woman …1900 Eng. dial.
– NANNY-HAMMER a foolish person …1881 Eng. dial.
– NARNA a fool, an idiot, an incompetent …1960s sl.
– NATURAL FOOL one who is by nature deficient in intelligence; a fool or simpleton by birth …c1430
– NATURAL IDIOT † one who is by nature deficient in intelligence; a fool or simpleton by birth …1540
– NAUMPEY a weak, foolish-minded person …Bk1905 Eng. dial.
– NAZOLD a silly or weak-minded person; a vain fool …1607 colloq.
– NAZZARD an insignificant or feeble person; a worthless scamp; a silly, foolish fellow …1619 obs. exc. Eng. dial.
– NEDDY a fool, a simpleton …1793 Sc. & Eng. dial.
– NENA a fool, an idiot, a ninny …1870 Eng. dial.
– NERK a fool; a generally unacceptable person …1950s sl.
– NERVOUS NELLIE, NERVOUS NELLY a fearful, foolish, and timid person …1920s US sl.
– NIB a fool …Bk1902 printers’ sl.
– NICKIN a fool, a simpleton …L17 sl.
– NICK-NINNY † a simpleton, an empty fellow, a fool …c1696 sl. or Eng. dial.
– NICKUMPOOP a fool; an oaf; a jerk …L17 sl.
– NIDDICOCK †* a fool, a simpleton, a ninny …1586
– NIDDIPOL a fool …1583 sl.
– NIDDLETY-NOD a foolish person …B1900 Eng. dial.
– NIDDY-NODDY a fool, idiot, or simpleton …1889 Eng. dial.
– NIGGET † a fool, simpleton, idiot …B1900
– NIG-NOG a foolish person …1953 Brit. sl.
– NIKEY a fool, a simpleton …L17 sl.
– NIKIN a fool, a simpleton …L17 sl.
– NIMSHI, NIMSHY a conceited fellow; a foolish fellow; a nincompoop; one who habitually acts in a foolish manner; a mischievous child  …1848 Amer. dial.
– NINCOMPOOP a foolish person …1676
– NING-NANG a worthless or troublesome person; an unreliable person; a silly or stupid person; a fool …1832 Eng. dial.
– NINGNONG a fool, an idiot, a stupid person …1832
– NINKOMPOOP a fool; an oaf; a jerk …L17 sl.
– NINNY a fool; an oaf; a simpleton …1533
– NINNYHAMMER a stupid or weak-minded person; a simpleton, a fool …1592
– NINNY-NONNY a silly, weak-minded, or foolish person …1823 Eng. dial.
​- NINNY-WHOOP †* a fool, a simpleton, a ninny …1653
– NISEY † a fool; a silly fellow; a simpleton; a dunce …c1684-6
– NIT a nitwit; an oaf; a fool …1588 colloq.
– NITWIT a simpleton, a moron, a fool …1914 US sl.
– NIZY a fool; a dunce …L17 sl.
– NIZZIE a fool; a dunce; a soft-head …L17 sl.
– NOCKY † a silly, dull fellow; a foolish person; a simpleton, a dullard; an oaf …a1700 obs. rare exc. Eng. dial.
– NOCKY BOY a dull oaf; a fool …17C colloq.
– NODCOCK a simpleton; a fool; an oaf …M16
– NODDIPOL an oaf; a fool …16C colloq.        
– NODDY an oaf; a fool; a simpleton …16C colloq.
– NODDY-HEAD an oaf; a fool; a simpleton …16C colloq.
– NODDY-PATE a simpleton, an idiot, a fool, an oaf …1660
– NODDY-PEAK(E) an oaf; a fool; a simpleton …16C colloq.
– NODDY-POLE an oaf; a fool; a simpleton …16C colloq.
– NODDY-POLL an oaf; a fool; a simpleton …16C colloq.
– NODGECOCK a simpleton; a fool; an oaf …M16
– NOGGY a young fool, a blockhead …B1900 Eng. dial.
– NOKES †* a fool, a simpleton, a ninny …a1700
– NONG an oaf; a dolt; a stupid person; a fool; an idiot …1944 Aust. sl.
– NONG-NONG a foolish person …1944 Aust. sl.
– NOODLE a foolish person …1753 sl.
– NULLY a foolish person …1973 sl.
– NUMB CREATURE a fool, a stupid person …1941 Amer. dial.
– NUMBHEAD a fool, a stupid person …1941 Amer. dial.
– NUMB NUT a fool, a stupid person …1966 sl.
– NUMBSKULL, NUMSKULL a fool; a blockhead; a dull-witted person; a dunce; a dolt; a stupid fellow …1742
– NUMBY a fool, a stupid person …1966 Amer. dial.
– NUM-CUMPUS one who is non compos mentis, or not of sound mind; a fool …1882 Eng. dial.
– NUMP a dolt; an oaf; a silly or stupid person; a fool; a blockhead …17C Brit.
– NUMPS † a silly or stupid person; a fool, a blockhead, a dolt …1611 obs. exc. Eng. dial.
– NUMPTY a fool; an idiot …Brit. sl.
– NUMPY a fool, a dolt …1941 Amer. dial.
– NUPSON † a simpleton, a fool …1607
​- NUT a crazy or insane person; an eccentric; a foolish person …1908 sl.
– NUTHATCH a madman; a fool …1972 Amer. sl.
– NUTHOUSE a fool …1926 Amer. sl.
– OAF a half-wit; a simpleton; a fool; a stupid fellow; a blockhead; an idiot; a dolt; an awkward, blundering lout; the clown of a circus …1638
– OAFO an oaf; a socially inferior fool; a lout …1959 UK sl.
– OANSHACH a foolish person, an idiot …1950 Sc.
– OANSHAGH a female fool …Bk1910 Ireland 
– OASHACH a foolish person, an idiot …1950 Sc.
– OHMADAUN a fool …M19 Ireland
– OINSEACH a female fool …2001 Irish sl.
– OLD BAT a disagreeable, middle-aged or elderly woman; an unpleasant or despicable female; an unattractive or foolish old woman …1886 UK sl.
– OLD BUFFER a foolish old person …1749 Brit. sl.
– OLD COOT a foolish or cantankerous old person; also used affectionately …M18 sl.
– OLD FART a fool, an unpleasant person, older than the speaker …M18 sl.
– OMADAUN a stupid person; a simpleton, a fool; a lazy, good-for-nothing fellow …1843 Ireland
– OMADAWN a fool …M19 Ireland
– OMADHAUN a fool, a simpleton; a dull, stupid person; a term of abuse …1818 Ireland
– ONE a fool, a dupe …1980s sl.
– OOK a jerk, a fool, a stupid person …1949 Amer. sl. 
– OONCHOOK a foolish person …1937 Irish & Can.
– OONSHI(C)K a fool or simpleton; a clot…1825 Irish & Newfoundland sl. 
– OONSHUGH a foolish woman …Bk1905 Ireland
– OYSTER an odd, stupid, or foolish person …1930s US sl.
– PAEPS a foolish youth …Bk1869 Eng. dial.
– PAISAN a fool …1950 Amer. dial.
– PAISANO a fool …1950s sl.
– PAMPOEN a fool …1940s S. Afr. sl.
– PANHANDLE a fool; an unpleasant person …1990s sl.
– PANTALOON † a term of contempt applied to an enfeebled, tottering old man; a dotard, an old fool …1596-1600
– PANWIT a fool …1990s UK juvenile sl.
– PAPER HAT a fool …1960s rhyming sl. for ‘prat’
– PAPER SCULL a fool …L17 sl.
– PAPER SKULL a fool …L17 sl.
– PAPES a foolish youth …Bk1905 Eng. dial.
– PAPPYSHOW a fool, or someone who presents the appearance of a fool; one who makes a stupid exhibition of themselves …1940 Trinidad and Tobago
– PASTIE a fool; used as a friendly term of abuse …2004 UK sl.
– PATTIC(K) a fool, simpleton, a silly person; one who talks nonsense; a merry fellow …1856 Eng. dial.
– PEA-BRAIN (derogatory) a foolish or unintelligent person …1938 colloq.
– PIE EATER * (derogatory) a contemptible person; a fool; a country bumpkin; also, a person who accepts political favours …a1891 US sl.
– PIE-FACE a foolish person …1922 US sl.
– PIGEON a fool; a soft-head …Bk1891 sl.
– PIG-SCONCE a pig-headed fellow, a blockhead, a fool, a dullard …1631
– PILLOCK a foolish man …1967 Brit. sl.
– PISS-HEAD an oaf; a fool; a jerk …20C US sl.
– PLONKER a foolish person …1966 Brit. sl.
– POGGLE † a crazy or foolish person; an idiot …E19 Indian now rare or obs.
– POON (derogatory) a simple or foolish person …1940 Aust. sl.
– POOP a foolish person …1915 sl.
– POPPY SHOW foolishness, showing off; one who makes a stupid exhibition of themselves …L19 W. Indies
– PORK a fool …1970s sl.
– POSSUM * a fool, a simpleton, a gull …1945 Aust. sl.
– POTATOHEAD a fool, a simpleton, a stupid person, a dunce, an oaf …1952 Amer. sl.
– POTHEAD a fool; a blockhead; a stupid person …1825 sl.
– POTTY a fool …1950 UK sl.
– POTTY-CLOCK a foolish person …Bk1862 Eng. dial.
– POT-WALLOPER (derogatory) a fool, a stupid person; also, an impostor, an upstart …1820
– PRAT a foolish person …1968 Brit. sl.
– PRAWN a person likened to a prawn in appearance or character, esp. in being foolish or foolish-looking …1845
– PRIZE PACKAGE a fool …1920s US sl.
– PRONK a foolish person …1959 sl.
– PROPER CHARLIE, A a foolish person …1946 sl., chiefly Brit.
– PROPER CHARLEY, A a complete fool …c1960 sl.
– PUDDEN a fool …Brit. sl.
– PUDDING a fool …Brit. sl.
– PUGGLE a crazy or foolish person; an idiot …E19 Indian now rare or obs.
– PUMBLECHOOK a stupid person; a fool; an oaf; a ‘human ass’ …L19 Brit. & US sl.
– PUPPY SHOW foolishness, showing off; one who makes a stupid exhibition of themselves …L19 W. Indies
– PUTTY-HEAD a fool; a stupid person …1905 Amer. dial.
– PUTZ a foolish, clumsy, or unfortunate person …1964 Amer. sl.  
– QUAD a very clumsy, stupid person; an inept fool …1977 US college sl. 
– QUASHIBA a foolish, uncultivated woman …1940s W. Indies sl.
– QUEER a fool, a simpleton …1950s Aust. sl.
– QUEER CULL a foolish dandy, a fop …L17 sl.
– QUILT a fool, someone who acts against their own interests …20C Irish sl.
– QUIMMO a fool; an unpleasant person …1999 UK sl.
– QUINCE a weakling; a fool …20C Aust. & US sl.
– RAASHOLE a derogatory description of a person; a general term of abuse; a contemptible person; a great fool; an idiot …1959 W. Indies & UK Black sl.
– RABBIT a simpleton; a fool; a silly person; a victim …1900 Aust. sl.
– RADGEPOT an idiot; a fool …1979 UK sl.
– RAFE a fool, a stupid person …Bk1904 Eng. dial.
– RAFFLE-TOPPIN(G) a wild, reckless, foolish person …19C Eng. dial.
– RAG a fool …1960s sl.
– RAISIN-BRAIN a fool; a term of abuse …1990s US Black sl.
– RALPH a fool; an oaf …18C colloq.
– RALPH-SPOONER a fool …L17 Eng. dial.
– RAWNY a silly fellow; a fool …B1900 Eng. dial.
– RIGHT CHARLEY, A a complete fool …c1960 sl.
– RIGHT CHARLIE, A a foolish person …1946 sl., chiefly Brit.
– RIGHT NANA a fool, an idiot, an incompetent …1960s sl.
– RODNEY a fool …M19 Eng. dial. & colloq.
– RUMMY a foolish person; a weak-minded person …1912 US sl.
– S.A.B. a Social Airhead Bitch …1980s US college sl.
– SADDLE-GOOSE † a nickname for a fool …1526
– SAINT-AGNES TÔTLE a stupid old fool …Bk1904 Eng. dial.
– SAM a fool, a simpleton …a1790 sl.
– SAM-DINGLE a term of contempt for a fool; a simpleton …Bk1904 Eng. dial.
– SAMMY a simpleton, a fool; an ill-natured fellow; an effeminate weakling; a lunatic …1876 Eng. dial.
– SAMMY BILLY a simpleton; a foolish, stupid person …Bk1887 Eng. dial.
– SAMMY CODLIN a simpleton; a foolish, stupid person …1889 Eng. dial.
– SAMMY DAWKIN a simpleton; a foolish, stupid person …1879 Eng. dial.
– SAMMY DINGLE a simpleton; a foolish, stupid person …Bk1887 Eng. dial.
– SAMMY-HEAD a simpleton; a foolish, stupid person …Bk1904 Eng. dial.
– SAMMY NODDY a simpleton; a foolish, stupid person …Bk1875 Eng. dial.
– SAMMY SOFT a fool; an oaf …c1840 sl.
– SAMMY SUCK-EGG a simpleton; a foolish, stupid person …Bk1896 Eng. dial.
– SAP a simpleton; a blockhead; a fool …1817 Sc. & Eng. dial.
– SAPADILLO a simpleton; a blockhead; a fool; a dunce …1817 sl.
– SAP-CRUST a fool; a blockhead …1899 Sc.
– SAPEROO a gullible person; a dupe; a complete fool …1950 Amer. sl. 
– SAP-HEAD a fool; a simpleton; a stupid person; a blockhead …1798
– SAPOLIO a simpleton; a blockhead; a fool; a dunce; a dupe …1817 sl.
– SAPOLO a simpleton; a blockhead; a fool; a dunce …1817 sl.
– SAPP a simpleton; a blockhead; a fool; a dunce …1817 sl.
– SAP-PATE † a fool, a simpleton …a1700
– SAPPER a simpleton; a blockhead; a fool; a dunce; a dupe …1817 sl.
– SAPPO a simpleton; a blockhead; a fool; a gullible person; a dunce; a dupe …1817 sl.
– SAPPY a fool; a blockhead …1868 Eng. dial.
– SAPPY-CRUST a blockhead, a fool …Bk1904 Eng. dial.
– SAPPYHEAD a fool …M19 sl.
– SAP-SCAUP a simpleton; a fool; a blockhead …Bk1873 Eng. dial.
– SAPSCULL, SAPSKULL † a silly fellow, a fool, a blockhead, a simpleton …1735 obs. exc. Eng. dial.
– SAP-TOPPIN a simpleton; a fool; a blockhead …1876 Eng. dial.
– SARDINE a term of reproach or abuse; a fool; a simpleton; a stupid fellow; a dullard …1857 US sl. 
– SART-AND-FAIR a foolish, weak person; one easily imposed upon …1777 Eng. dial.
– SART-POLL a foolish, weak person; one easily imposed upon; a good-for-nothing fellow …1867 Eng dial.
– SATEPOLL a foolish, silly, or stupid person; a simpleton …1867 Eng. dial.
– SAUSAGE someone foolish or gullible; used as a gently reproving term of address …1982 UK sl.
– SAWN a foolish person …1953 Aust. sl.
– SAWN(E)Y a simpleton, a fool, a stupid fellow; a soft, good-natured fellow …a1700 colloq.
– SCART a saving, industrious person; a niggard; a villain; a fool …1895 Sc. & Eng. dial.
– SCHLEMASEL, SCHLEMAZEL a fool, esp. an unfortunate, an incompetent …L19 sl.
– SCHLEMBO a fool …2000s sl.
– SCHLEMIEL, SCHLEMIHL, SHLEMIEL a fool; a clumsy person; a gullible person; an ineffectual or incompetent person …1892 sl., chiefly US
– SCHLEP(P), SHLEP a foolish person …1939 sl., chiefly US
– SCHLEPPER, SHLEPPER a foolish person …1954 sl., chiefly US
– SCHLOOMP, SHLOOMP a foolish person …1948 sl., orig. & chiefly US
– SCHLUB, SHLUB an oaf or dolt; a fool …1964 US sl.
– SCHLUCK, SHLUCK a clumsy, uncoordinated fool …Brit. sl.
– SCHLUMP, SHLUMP a foolish person …1948 sl., orig. & chiefly US
– SCHMENDRIK, SHMENDRIK a foolish person …1944 US sl.
– SCHMO, SHMO a foolish person …1948 sl., chiefly US
– SCHMOCK, SHMOCK a stupid person; a fool; oaf; …20C US sl.
– SCHMUCK, SHMUCK a foolish person …1892 sl., chiefly US
– SCISSOR one regarded as foolish, incompetent, or inexperienced …1916 Amer. dial.
– SCISSORS-BILL one regarded as foolish; an ineffectual, incompetent, or inexperienced  person …1871 sl., chiefly US
– SCIZZOR-BILL one regarded as foolish, incompetent, or inexperienced …1940 Amer. dial.
– SCRUB a fool, a stupid person, a dumb individual …1980s US Black sl.
– SEMOLIA a fool; a stupid person …1890s US Black sl.
– SHALLOW-PATE a person having no depth of intellect or understanding; a foolish or empty-headed person …1600
– SHEEPSHEAD † a foolish or stupid person …1542
– SHITTY-WATTY a weak-headed, foolish person …B1900 Eng. dial.
– SHLEMOZZLE a fool, esp. an unfortunate, an incompetent …L19 sl.
– SHOON a fool; a bumpkin; a lout …19C cant
– SIDE-SIM a fool; a simpleton …E17 sl.
– SILLIKEN, SILLIKIN a fool, a simpleton …1860 sl.
– SILLY a silly or foolish person …1858 colloq.
– SILLY-ARSE a fool …1943 Aust. sl.
– SILLY ASS a foolish or stupid person …1608
– SILLY BILLY a fool, a simpleton …1834 sl.
– SILLY BOLLOCK(S) a contemptible fool; an idiot …1999 UK sl.
– SILLY CUNT a fool …2000 UK sl.
– SILLY GOOSE a fool …Bk1995 US sl.
– SILLY LEGS a term of mild abuse aimed at someone behaving like a fool …Brit. sl.
– SILLYPOP a fool; a foolish, flighty woman …L19 sl.
– SILLY WILLY a fool; a simpleton …M17 sl.
– SIM a fool; a simpleton; a confidence trickster’s dupe …20C Aust. criminals’ sl.
– SIMKIN * a fool; a simpleton …a1700
– SIMON a fool; a soft-head …Bk1891 sl.
– SIMP a fool, a simpleton, an oaf, a stupid or dull person; a dim-witted or backward person …c1910 sl., orig.
– SIMPKIN a fool; a simpleton …1861 rare
– SIMPLE an ignorant or foolish person …1643
– SIMPLER a simple or foolish man much given to lust …L16 sl.
– SIMPLE SIMON a silly fellow; a credulous gullible person; a fool, a simpleton …1785 sl.
– SINGLE-TEN a very foolish, silly fellow …a1700 sl.
– SIR ANTHONY (BLUNT) a fool; a despicable fool …1979 UK rhyming sl. for ‘cunt’
– SIZZER one regarded as foolish, incompetent, or inexperienced …1932 Amer. dial.
– SKEEZIX a fool …1975 US sl.
– SKITTER-WIT a flighty person; a foolish, harebrained fellow; a scatterbrain …1886 Eng. dial.
– SKITWIT a soft, foolish, scatterbrained person …B1900 Eng. dial.
– SLOW-COACH a fool; a soft-head …Bk1891 sl.
– SNORKER a contemptible fool …1977 US sl.
– SOAP a fool, a simpleton …1950s Aust. sl.
– SOFT-HORN a fool; a soft-head …Bk1891 sl.
– SOFTIE, SOFTYa person who is sentimental, weakly foolish, or lacking in physical endurance …1886
– SOP a fool; a soft-head …Bk1891 sl.
– SOPPY DATE a foolish or silly person …1914 UK sl.
– SPACE CADET a foolish person; a person who is always silly or giddy …1973 sl.
– SPACKHEAD a fool; an eccentric person …2003 UK juvenile sl.
– SPALT †* a silly or foolish person …1639
– SPANGLE a fool; a very stupid person …2001 Sc. juvenile sl.
– SPANNER a fool; a stupid person; an idiot …1987 sl.
– SPANNER-HEAD a fool; a stupid person; an idiot …1990 Aust. sl.
– SPARKY a fool; a mentally handicapped person …2003 UK sl.
– SPAS, SPAZ(Z) (derogatory) a spastic person; an ineffectual or incompetent person; a fool; an idiot; a stupid person; a clumsy, unattractive person …1965 sl.
– SPASTIC – (offensive) one who is uncoordinated, ineffectual, or incompetent; a fool; an idiot; a stupid person; a clumsy, unattractive person …1968 sl.
– SPAZ-WIT a fool, an idiot, a stupid person .,..1998 UK sl.
– SPOON a fool, a simpleton …L18 sl.
– SPOONEY a fool, a simpleton …L18 sl.
– SPOONY a fool, a simpleton …L18 sl.
– SQUIRE, THE a simpleton, a fool …L17 sl.
– S.S. a fool; (Sammy Soft) …c1840 sl.
– STEAMER a fool; a victim …1932 UK sl.
– STEAM TUG a fool; a victim …1932 UK rhyming sl = mug
– STIFFY a foolish person …1965 US sl.
– STRACKLE-BRAIN a giddy, thoughtless person; a simpleton, a fool; a good-for-nothing …1877 Eng. dial.
– STRUT-NODDY a mincing fool …Bk1904 sl.
– STUB a fool; an oaf…1632-74 sl.
– STUMP an oaf; a fool; a blockhead…19C Brit. sl.
– STUPE a foolish person …1762 sl.
– SUCK-EGG a fool, a silly person, a stupid fellow …1609 Eng. dial. & sl.
– SUMPH a fool, a blockhead …1682 Sc. & Eng. dial.
– TACK a fool …1974 US Black sl. 
– TAME CAT a person who is made a convenience by his friends; a foolish fellow, a simpleton …1885
– TAME-FELLOW † a person who is made a convenience by his friends; a foolish fellow, a simpleton …a1700
– TAME-GOOSE † a foolish fellow; a simpleton …1605
– TAMMY a simpleton, a fool …Bk1905 Eng. dial.
– TAMMY-NORRY a simpleton, a foolish person …Bk1905 Eng. dial.
– TAPLOCH † a giddy, foolish girl …1824 Sc.
– TAPPY a foolish, giddy, awkward, idle, or slovenly girl …1824 Sc.
– TARD a dolt; a fool; a stupid person …Bk1994 US teen & college sl.
– TARRY ROPE a fool …1944 rhyming sl. for ‘dope’
– TART a fool, male or female …1999 sl.
– TASS(E)Y, TAZIE, TAZZY a mischievous child; a foolish, romping girl; a silly fellow …1808 Sc. & Eng. dial.
– TATA a foolish person …1966 UK sl.
– TATARAM a foolish old man, esp. one with sex on his mind …1996 W. Indies
– TAUPIE, TAWPIE, TAWPY a foolish, giddy, scatterbrained, untidy, awkward, or careless person; an idle or slovenly person; generally applied to young women …1728 Sc.
– TAWPLOCH  a giddy, foolish girl …Bk1824 Sc.
– TETAW a simpleton, a fool …Bk1905 Eng. dial.
– THICK a foolish person …1857 sl., orig. schoolchildren’s usage
– THICKHEAD a fool; a soft-head …Bk1891 sl.
– THICKIE a foolish person …1968 sl.
– THICKO a foolish person …1976 sl.
– THITER a foolish fellow; an idiot …Bk1905 Eng. dial.
– THOMAS a fool, a simpleton …1934 Sc.
– THRUM-YED a foolish fellow …Bk1905 Eng. dial.
– TIN EAR a fool; a simpleton …1930s Aust. & US sl.
– TIN HAT a fool …1960s rhyming sl. for ‘prat’
– TIT a foolish person …1947 sl.
– TITTLE-GOOSE a foolish, tattling person; a telltale, a foolish blab …1807 Eng. dial.
– TOM a man, esp. a foolish one …M16 sl.
– TOM FARTHING a fool, a simpleton …1689
– TOM FOOL a foolish or stupid person; one who behaves foolishly …1721
– TOMMY a simpleton, a fool …1829
– TOMMY-NODDY a foolish or stupid person …1828
– TOM-NODDY a foolish or stupid person; a blockhead, dunce, dolt, simpleton …1828
– TOM TUG a fool; a soft-head …Bk1891 sl.
– TONEY, TONY † a foolish person; a simpleton …1654 sl.
– TONK a foolish person …1941 sl., chiefly Aust.
– TOOL a fool …sl.
– TOOT an idle or worthless person; a shiftless, lazy person; a simpleton, a fool; an oaf …1888 Eng. & Amer. dial.
– TROANT  a foolish, idle person; a lazy loiterer …1746 Eng. dial.
– TRONK an idiot; a foolish person …1970s UK teen sl.
– TRONK-HEAD an idiot; a foolish person …1970s UK teen sl.
– TUNKLEHEAD a fool …1941 Amer. dial.
– TURKEY an idiot, a fool …Bk1995 US sl.
– TWALLY an idiot; a fool …1996 Sc. sl.
– TWERP, TWIRP a foolish person …1874 sl.
– TWINK a jerk; an incompetent fool …20C US sl.
– TWIT a foolish person …1934 sl., chiefly Brit.
– UDDER a despised, disrespected or foolish woman …2001 UK sl.
– UGMA a fool; a (potential) victim …1956 Aust. criminals’ sl.
– UGMAY a ‘sucker’, a dupe, a gullible person; a fool, or a stupid person …1918 US Pig Latin for ‘mug’
– UM-CHAW a doltish, naive person; a foolish or stupid person; a dupe, a gullible person …1910 Pig Latin for ‘chump’ 
– UMPCHAY a doltish, naive person; a foolish or stupid person; a dupe, a gullible person …1910 Pig Latin for ‘chump’ 
– UNCHAGHE † a foolish or wanton woman …1534
– UNCONSCIOUS a fool …1920s US college sl.
– UNWISEMAN † a fool, a simpleton …1400
– UTZPAY a fool, an idiot …1930s Pig Latin for ‘putz’ 
– VEAL a fool, a simpleton …c1642 UK sl.
– WACKER, WHACKER a fool; a stupid person …1965 Aust. sl.
– WACKY a fool, simpleton, blockhead …Bk1903 Eng. dial.
– WAD a fool, an idiot, an unpleasant person …1900 sl., orig. US college usage
– WAD-WASTE a term of abuse; a fool, an idiot, an unpleasant person …1981 sl., orig. US college 
– WAFFLE-BAGS a foolish person who talks much, and foolishly …1884  Eng. dial.
– WALLY a foolish person …1969 Brit. sl.
– WANT-WIT one who lacks wit or sense; a fool …1448-9
– WARB a fool, a simpleton …1955 Aust. sl. 
– WATERHEAD a foolish person …1960s sl.
– WATTY a simpleton; an indiscreet or foolish person …B1900 Eng. dial.
– WAZZOCK a foolish person …1983 Brit. sl.
– WEAPONHEAD a foolish person …1980s Aust. prison sl.
– WET an ineffectual, weak, foolish person …1930s sl., orig. UK juvenile usage
– WET END an ineffectual, weak, foolish person …1930s sl., orig. UK juvenile usage
– WETSO an ineffectual, weak, foolish person …1930s sl., orig. UK juvenile usage
– WHACKER a fool …1960s Aust. sl.
– WIDGEON † applied to a person, in allusion to the supposed stupidity of the bird; a fool, a simpleton …1612
– WIGEON a fool, a simpleton …E17 arch.
– WILF a fool …Bk2004 UK sl.
– WILLY WONKA a fool …1998 UK sl. for ‘plonker’
– WISE MAN OF GOTHAM, A  a foolish person …1737
– WITLING a fool, a simpleton …Bk1905 Sc.
– WITTY a fool; a mentally retarded person …1940 Amer. dial.
– WOMBLE a foolish, clumsy, or unfortunate person; a socially inept person …1985 UK sl.
– WOODCOCK a gullible fool; an oaf …15C
– WOODENTOP a fool; a slow-witted person …1983 Brit. sl. 
– WOZZ a fool; an idiot …Brit. sl.
– WOZZLE a fool; an idiot …Brit. sl.
– WUL a fool …Brit. sl.
– WULBERT a fool …Brit. sl.
– YABO a fool …1925 sl.
– YACK, YAK a fool; a stupid fellow; an oaf; an innocent person; a dope …c1920 US sl. 
– YAP a foolish person; a simpleton; one slightly weak in intellect …c1894
– YAPPY a foolish person; one slightly weak in intellect …Bk1905 Eng. dial.
– YAP-STICK a foolish person; one slightly weak in intellect …Bk1905 Eng. dial.
– YARD DOG a fool; a gullible person …1930s US Black sl.
– YASHA an idiot; a fool; a dolt …Bk1972 homosexual sl. 
– YAUP, YAWP one who has a vacant stupid look; a fool, an oaf, a yokel …1896 Sc.
– YAWKY a foolish or maladroit person …Bk1887 Eng. dial.
– YAWNAX a stupid person; a fool; a lazy, uncouth person; a boor …1870 Eng. dial.
– YAWN(E)Y, YORNEY a stupid, lazy, sleepy person; a fool …1777 Eng. dial.
– YAWNUP a stupid person; a fool; a lazy, uncouth person; a boor …1870 Eng. dial.
– YAWNUPS a stupid person; a fool; a lazy, uncouth person; a boor …1870 Eng. dial.
– YAWNUX a stupid person; a fool; a lazy, uncouth person; a boor …1870 Eng. dial.
– YAZZIHAMPER † a farmer; a rustic; a fool, a sucker …1933 criminals’ sl.
– YERQUICK an absolute fool; a really dumb person …2001 Aust. sl.
– YOB * a fool; a naive, gullible, or unintelligent person; a dupe; also, an unsophisticated person; a country bumpkin …1886 chiefly Aust. & NZ
– YOBBO a foolish, unsophisticated idiot …Bk1988 Aust. sl.
– YOCKER a foolish person or bumpkin …Bk2002 criminals’ sl.
– YOK a man; a fool. a chump …1934 sl.
– YONNACK a fool, a harebrained fellow …Bk1887 Eng. dial.
– YOTZ a fool, an idiot …1983 US sl.
– YOYO an unpredictable or inconsistent person whose moods and actions go up and down; hence, a fool; an idiot, a dolt; a stupid person; an obnoxious person; an incompetent, or undesirable person; a jerk …1959 US sl.
– YUCK, YUK  a fool; a stupid fellow; an oaf; an innocent person; a rustic …1943 sl., orig. US
– YUTZ a fool, an idiot; a simpleton; a failure …1983 US sl.
– ZAMMY a simpleton, a fool; an ill-natured fellow; an effeminate weakling; a lunatic …1876 Eng. dial.
– ZANY a fool, a simpleton …a1784
– ZAPE a blockhead; a fool …Bk1882 Eng. dial.
– ZAPP a simpleton; a blockhead; a fool; a dunce …1817 sl.
– ZAPY a blockhead; a fool …Bk1882 Eng. dial.
– ZATENFARE a foolish, weak person; one easily imposed upon …1777 Eng. dial.
– ZHLOB an oaf or dolt; a fool, a moron; a boorish, insensitive person; a coarse person, a slob …1950 US sl.
– ZHLUB an oaf or dolt; a fool, a moron; a boorish, insensitive person; a dull, unpolished person, usually a male …1950 US sl.
– ZIB a nincompoop; a fool, a sucker; an oaf; a stupid person with unknown political or personal opinions …1934 US sl., chiefly criminals’ usage
– ZIP a worthless person; a person who amounts to zero; an insignificant person; an unpleasant person with no good qualities; a fool; a sucker …1971 US sl.
– ZIPALID a complete fool …1970s US sl.
– ZIPPERHEAD (derogatory) a stupid person; a fool …1967 US sl.
– ZIPPERLID a complete fool …1970s sl.
– ZIPPO an insignificant person; an unpleasant person with no good qualities; a fool; a sucker …1987 US sl.
– ZIP SACK an insignificant person; an unpleasant person with no good qualities; a fool; a sucker …1982 US sl.
– ZIRCON a fool …1968 US sl.
– ZOB * a weak or contemptible person; a fool; a good-for-nothing; a worthless person; a nobody …1911 US sl.
– ZOKE a fool, a dolt …Bk1886 Eng. dial.
– ZOKEY a sawney; a foolish person …Bk1855 Eng. dial.
– ZONK a fool; a dolt; an idiot …Bk1988 Aust. & NZ
– ZOOMER an energetic fool …2000 UK sl.
– ZOT(E)Y – a fool; an idiot …Bk1855 Eng. dial.
fool – verbs  (also see BEFOOL, FOOL ABOUT ) (includes foolish)
– ACE OUT to fool someone; to swindle someone …1933 US sl.
– ACT THE ANGORA to play the fool …1942 Aust. sl.
– ACT THE GIDDY GOAT to behave foolishly …L19 sl.
– ACT THE GOAT to behave foolishly …L19 sl.
– ACT THE HOG to play the fool …1900s sl.
– ACT THE MAGGOT to play the fool …1937 Irish sl.
– ACT THE MONKEY to play the fool …1900s sl.
– ACT THE JINNIT to play the fool; to act irrationally …20C Irish sl.
– ACT THE NIGGER 1. (derogatory) to play the fool …M19 US sl.
  2. to act in a manner White racists expect of Black people, i.e. foolish, subservient, clownish …M19 US Black sl.
– ACT THE PRICK to behave foolishly …1980s sl.
– ADOLESCENTURATE † to play the boy, or fool …1626
– ASS OUT to make a fool of oneself …1990s US college sl.
– BAFFLE † to hoodwink, to gull, to cheat; to humbug; to make a fool of …c1590
– BAMFOOZLE to fool or swindle; to confuse …1851 Amer. dial.
– BEDAFF † to make a fool of, to make foolish …c1386
– BEDAW to make a fool of …a1529
– BEGAB † to fool with words, to mock, to deceive, to delude; to impose upon …1297
– BELIEVE THE MOON IS MADE OF CHEESE to believe firmly something astounding, impossible, or absurd; hence, to be a fool …18C colloq.
– BE NOT AS GREEN AS ONE IS CABBAGE-LOOKING be less than a fool than might be assumed …colloq.
– BE WRONG IN ONE’S GARRET to be foolish or wanting in intellect, or suffering from temporary delirium …1869 sl.
– BIG-ASS to make a fool of …1984 US sl.
– BLIND to confound or stump someone; to fool …1916 Amer. college usage
– CHILL OUT to stop acting foolish …1981 US Black sl.
– CHUMP 1. to trick, to deceive; to make a fool of someone …1920s sl.
2. to act like a fool; to be exploited …1960s US Black sl.
– CHUMP OFF to act like a fool …1930s US Black sl.
– CHUMP OUT to trick, to deceive; to make a fool of someone …1920s sl.
– CLEAVE THE CLOUDS to act foolishly and to no purpose …B1900
– COME ON ONE’S GUAVA to make a fool of oneself …1970s S. Afr. sl.
– COME THE ABDABS to fool someone …1940s sl.
– COME THE OLD ABDABS to hoax, to fool …1940s sl.
– CONFISCATE THE MACAROON to ‘take the biscuit’; to be the most remarkable or foolish of its kind …c1918 Brit. sl.
– COUGH ONE A DAW † to make a fool of, to befool …a1529
– CRAP AROUND to waste time; to behave foolishly or aimlessly …1935 US sl.
– CROWN WITH A MAROTTE † to make a fool of …1630
– CUDDLE AND KISS to make a fool of, to ‘take the piss’ …1992 UK rhyming sl.
– CUT A BIG GUT to do something foolish …Bk1942 Amer. sl.
– DAFF to play the fool …1535 chiefly Sc.
– DESERVE THE BAUBLE † to make a fool of …1606
– DO ONESELF to make a fool of oneself; to embarrass oneself …1980s US sl.
– DUD to fool or deceive; to swindle …1970 Aust. sl.
– DUKE to fool; to deceive …1975 US sl.
– EAT ONE’S NAILS to do something foolish …E18 sl.
– FAKE to trick, to fool; to cheat; to swindle; to deceive …1859 sl.
– FAKE OUT to fool an opponent with a feint; hence, generally, to bluff, to fool; to get the better of; to dupe, to deceive …1949 Amer. sl., orig. football & basketball usage
– FART ABOUT to dawdle, to mess around, to potter, to waste time in trifling activity; to behave foolishly or aimlessly …1910s sl.
– FART AROUND to dawdle, to mess around, to potter, to waste time in trifling activity; to behave foolishly or aimlessly  …1969 sl.
– FATUATE to become silly, to act foolishly, to play the fool …1656 arch.
– FILL to fool; to provide with misinformation …1968 Amer. dial.
– FILL UP to fool; to provide with misinformation …1879 Amer. dial.
– FLAM to swindle, to fool, to deceive …1637
– FLUMMOX, FLUMMUX to fool, to confuse, to overcome by trickery; to bewilder …1837 sl.
– FOOLIFY † to make a fool of; to befool …1581 obs. exc. Eng. dial.
– FOOTLE to talk or act foolishly; to do anything in a feeble or ineffectual manner; to dawdle, to trifle, to potter; to idle, to waste time …1892 sl.
– GAME † to befool, to jeer at, to mock, to delude …1698 UK sl.
– GAMMON to deceive, to fool, to talk humbug,…1812
– GIVE A RIDE to deceive, to fool, to trick, usually for financial gain …1920s sl.
– GIVE SOMEONE THE ABDABS to fool someone …1940s sl.
– GIVE SOMEONE THE GUY to make a fool of someone; to tease …19C sl.
– GIVE SOMEONE THE OLD ABDABS to fool someone …1940s sl.
– GIVE THE BAUBLE † to make a fool of, to befool …1599
– GREEN to tease, to make a fool of; to annoy with practical jokes; to outwit …1923 Amer. dial.
– GREEN ON to tease, to make a fool of; to annoy with practical jokes; to outwit …1887 Amer. dial.
– GREEN OUT to tease, to make a fool of; to annoy with practical jokes; to outwit …1887 Amer. dial.
– GUCK † to trifle; to play the fool …c1560 Sc.
– GYPE to play the fool; to mess around …1825 Sc. & Eng. dial.
– HAIVER to talk in a foolish, incoherent manner …1816 Sc.
– HALLOCK to behave in a foolish, noisy way …Bk1905 Sc.
– HAVEREL to talk nonsense, to make a fool of …1822 Sc. & Eng. dial.
– HOLD A LOOKING-GLASS TO A MOLE to act foolishly and to no purpose …B1900
– IDIOTIZE to make a fool of; to befool …1831
– JACK ACT to play the fool …1920s Irish sl.
– JEFF to talk, to chatter, esp. to seduce, to fool or deceive with a ‘line’ …1960s US Black sl.
– JERK SOMEONE’S CHAIN to deceive, to fool, to victimize …Amer. sl.
– JERK SOMEONE’S STRING to deceive, to fool, to victimize …Amer. sl.
– LANT to jeer at; to gibe; to make a fool of …1861 Sc.
– LARK to play, esp. the fool; to be mischievously merry; to go on the spree …1813 colloq.
– LAY IT OVER to fool, to deceive …1878 Amer. sl.
​- LOSE OUT to be swindled or merely fooled …L19 Aust. sl.
– MACKY-MOON to play the fool …B1900 Eng. dial.
– MAFFLE to act or talk in a foolish way …Bk1905 Eng. dial.
– MAKE A MONKEY (OUT) OF to make a fool of; to deceive, to dupe; to ridicule …1767 sl., orig. US
– MOGE; MOGUE to deceive, to fool, to trick, to cheat, to humbug; to play a joke on, to make fun of …1854 sl., orig. Eng. dial.
– MONK to make a fool of …1916 Amer. dial.
– MORG to deceive, to fool, to trick, to cheat, to humbug; to play a joke on, to make fun of …1854 sl., orig. Eng. dial.
​- MUCK ABOUT to waste time; to behave foolishly or aimlessly …1856
– MUCK UP to play the fool …c1910 Aust. sl.
– NAFFLE to trifle away time; to potter about; to loiter; to act foolishly …1796 Sc. & Eng. dial.
– NANNICK to play the fool; to play when one should be working; to idle away one’s time; to fidget …Bk1905 Eng. dial.
– NANNOCK to play the fool; to play when one should be working; to idle away one’s time; to fidget …Bk1905 Eng. dial.
– NICK to fool …1593
– NIFF-NAFF to trifle; to toy; to take finicking trouble; to talk or act foolishly or aimlessly …1728 Sc. & N. Eng. dial.
– NONNOCK to play the fool; to play when one should be working; to idle away one’s time; to fidget …Bk1905 Eng. dial.
– NONNUCK to play the fool; to play when one should be working; to idle away one’s time; to fidget …Bk1905 Eng. dial.
– OAF to act in a foolish, childish manner; to play the fool …1882 Sc. & Eng. dial.
– OAF ABOUT to act in a foolish, childish manner; to play the fool …1882 Sc. & Eng. dial.
– PACK IT IN to stop talking; to stop fooling or some foolish practice …c1925 Services’ sl.
– PACK IT UP to stop talking; to stop fooling or some foolish practice …c1925 Services’ sl.
– PAPPY SHOW to make a fool of someone …L19 W. Indies
– PIDDLE ABOUT to behave foolishly, and esp. in a time-wasting way …1545 sl.
– PIDDLE AROUND to behave foolishly, and esp. in a time-wasting way …1545 sl.
– PISS ABOUT to waste time; to behave foolishly or aimlessly …1961 sl.
– PISS AROUND to behave foolishly, and esp. in a time-wasting way …1961 Brit. & Aust. sl.
– PLAY HORSE to play the fool or engage in horseplay …1892 US sl.
– PLAY OFF ON to deceive, to fool, to trick …1863 Amer. dial.
– PLAY SILLY BLEEDERS to waste time; to behave foolishly or aimlessly …1961 sl.
– PLAY SILLY Bs to waste time; to behave foolishly or aimlessly …1961 sl.
– PLAY SILLY BUGGERS to waste time; to behave foolishly or aimlessly …1961 sl.
– PLAY SOMEONE FOR A CHINAMAN (now considered offensive) to treat as a fool …1873 Amer. sl.
– PLAY THE GOAT to act the fool …L19 sl.
– PLAY THE JACK to act the fool …Bk1896 sl.
– PLAY THE MONKEY to play the fool …1900s sl.
– PLAY THE NANNY-GOAT to behave like a fool; to play foolish tricks …1900 Eng. dial.
– POPPY SHOW to make a fool of someone …L19 W. Indies
– PRAT ABOUT to behave foolishly, and esp. in a time-wasting way …1961 Brit. sl.
– PULL SOMEONE’S CHAIN to deceive, to fool, to victimize …Amer. sl.
– PULL SOMEONE’S PLONKER to fool someone; to tease someone; to take a liberty with someone…2000 UK sl.
– PULL SOMEONE’S STRING to deceive, to fool, to victimize …Amer. sl.
– PULL SOMEONE’S TIT to good-naturedly hoax or deceive someone; to make a fool of someone …1959 Aust. sl.
– PUPPY SHOW to make a fool of someone …L19 W. Indies
– PUT A ROPE TO THE EYE OF A NEEDLE to attempt the impossible or absurd; to act foolishly and to no purpose …B1900
– PUT THE CAP ON SOMEONE to fool them …1966 Amer. dial.
– RAG ABOUT to fool about …20C sl., orig. & chiefly university
– RATTLE SOMEONE’S CHAIN to deceive, to fool, to victimize …Amer. sl.
– RATTLE SOMEONE’S STRING  to deceive, to fool, to victimize …Amer. sl.
– ROAST SNOW IN A FURNACE to attempt the unnecessary or absurd; to act foolishly and to no purpose …1883 sl.
– RUN THE HOG to play the fool …1900s sl.
– SAWNEY to act the sawney, to fool …B1900
– SEEK A NEEDLE IN A BOTTLE OF HAY to attempt an extremely difficult, impossible, or foolish task …1690
– SEEK A NEEDLE IN A TRUSS OF HAY to attempt an extremely difficult, impossible, or foolish task …1711
– SELL AN OX TO CATCH A HARE to act foolishly …B1900
– SELL ANY ONE A BARGAIN † to make fool of him, to ‘sell’ him …1588
– SHOW A TRICK to outwit, to fool, to deceive …1982 NZ sl.
– SIMP to act like a fool …1960s US Black sl.
​- SLIP ON ONE’S GUAVA to make a fool of oneself …1970s S. Afr. sl.
– SPOOF to hoax, to fool, to trick …L19 sl.
– STOOGE to fool, to deceive …1990s Aust. sl.
– STRING to fool or hoax; to deceive, to dupe …1812 sl., chiefly US
– TAKE FOR A RIDE to deceive, to fool, to trick, usually for financial gain …1920s sl.
– TAKE FOR A TROT to deceive, to fool, to trick, usually for financial gain …1920s sl.
– TAKE THE PISS OUT OF of a person: to act absurdly, to play the fool …1990 sl.
– TAKE THE TA-TA to make a fool of someone; to pull someone’s leg, to tease …1992 UK rhyming sl. for ‘take the piss’ (take the ta-ta kiss)
– TAKE THE TA-TA KISS to make a fool of someone; to pull someone’s leg, to tease …1992 UK rhyming sl. for ‘take the piss’
– TALK TURKEY to talk foolishly …E19 sl., orig. US
– TATTER to make a fool of anyone …Bk1905 Eng. dial.
– TEACH IRON TO SWIM to act foolishly and to no purpose …1809
– TOM-FOOL to play the fool …1825
– TONY †* to make a fool of; to fool, to cheat, to swindle …a1652
– WALK DOWN ONE’S BACK to take one in; to make a fool of one …1867 Eng. dial.
– WEAR THE BELLS to act the fool …1931 Amer. dial.
– WRITE ON THE SURFACE OF THE SEA to act foolishly and to no purpose …B1900
– YANK SOMEONE’S CHAIN to deceive, to fool, to victimize …Amer. sl.
– YANK SOMEONE’S STRING to deceive, to fool, to victimize …Amer. sl. Dict
– YUCK IT UP to behave foolishly, and esp. in a time-wasting way …1961 sl., chiefly Amer.
– YUK IT UP to behave foolishly, and esp. in a time-wasting way …1961 sl., chiefly Amer.
fool – phrases 
– FOOL’S A MONKEY’S MASTER, A said to one who calls another a fool …B1900 Eng. dial.
– HE DOESN’T KNOW IF HIS ARSEHOLE IS BORED OR PUNCHED he’s a complete fool …E20 sl.
– I DIDN’T COME DOWN IN THE LAST SHOWER I’m not stupid; don’t take me for a fool …20C Aust. sl.
– I DIDN’T COME DOWN IN THE LAST SHOWER OF RAIN I’m not stupid; don’t take me for a fool …20C Aust. sl.
– I DIDN’T FALL OFF A CHRISTMAS TREE I’m not stupid; don’t take me for a fool …1940s sl.
– NOT SO GREEN AS I’M CABBAGE-LOOKING I’m not such a fool as I may appear …L19 sl.
– THERE ARE MANY WAYS OF DRESSING CALVES’ HEADS many ways of saying or doing a foolish thing; a simpleton has many ways of showing his folly; or, generally, if one way won’t do, we must try another …Bk1891 sl.
– THERE ARE NO FLIES ON HIM he is no fool
 
FOOL ABOUT, FOOL AROUND – nouns
– FUNNY BUSINESS nonsense; fooling around; later, action or behaviour that is deceptive, dishonest, or otherwise suspect …1882 colloq.
fool about, fool around – person
– FART-OFF a person who shirks responsibilities; a loafer; one who always fools around …1942 Amer. sl.
– PISS ARTIST a drunkard; a person who fools about; a feckless or irresponsible person …1962 colloq.
fool about, fool around – verbs 
– ANTIC to fool around, to play …1976 Amer. dial.
– ARSE ABOUT to idle, to fool about; to waste time …1664 Brit.
– ARSE AROUND to idle, to loaf, to loiter, to fool about, to act irresponsibly, to trifle …1664
– ASS AROUND to fool around, to loiter, to waste time; to wander aimlessly; to be idle; to act irresponsibly; to trifle …1914 Amer. sl.
– ASSEN AROUND to fool around; to loiter; to waste time; to be idle …1966 Amer. dial.
– BOLLIX AROUND to fool around …c1960 Amer. dial.
– BUGGER ABOUT to behave foolishly, and esp. in a time-wasting way …1929 Brit. & Aust. sl.
– BUGGER AROUND to behave foolishly, and esp. in a time-wasting way …1929 Brit. & Aust. sl.
– CAT to gad about; to fool around …1938 Amer. dial., chiefly among Blacks
– CAT AROUND to gad about; to fool around …1938 Amer. dial., chiefly among Blacks
– FADE to fool around or tinker with something or someone …1990s US Black teen sl.
– FAFF to mess about, restlessly and ineffectually, wasting time, often while something quite urgent needs attention; to play or fool around, to waste time …c1930
– FAFF AROUND to mess about; to waste time on matters of no importance; to play or fool around …1874 UK sl.
– FAFF ABOUT to behave foolishly, and esp. in a time-wasting way …1874 sl., orig. Eng. dial.
– FANDANGLE to hang about, to trifle, to waste time, to ‘fool’ around …1892 Ireland
– FART ABOUT to waste time; to behave foolishly or aimlessly …1900 sl.
– FART AROUND to dawdle, to mess around, to potter, to waste time in trifling activity; to behave foolishly or aimlessly  …1931 sl.
– FART OFF to fool around; to shirk one’s duties; to blunder through inattention; to procrastinate …1968 Amer. sl.
– FIDDLE-DEE-DEE AROUND to meddle, to fool around …1963 Amer. dial.
– FIDDLE-FART to fool around, to waste time. to loaf, to dawdle, to shirk responsibility …1975 Amer. dial.
– FIDDLE-FART AROUND to fool around, to waste time. to loaf, to dawdle, to shirk responsibility …1972 Amer. sl.
– FIDDLE-FOOT AROUND to fool around, to move restlessly …1963 Amer. dial.
– FIDDLEFUCK AROUND to fool around, to waste time. to loaf, to dawdle, to shirk responsibility …1984 Amer. dial.
– FOOZLE ABOUT to fool around …1930s sl.
– FUCK ABOUT to behave foolishly, and esp. in a time-wasting way …1922 sl.
– FUCK AROUND to behave foolishly, and esp. in a time-wasting way …1922 sl.
– FUTZ AROUND to behave foolishly, and esp. in a time-wasting way …1929 US sl.
– GAY-CAT to gad about; to fool around …1938 Amer. dial., chiefly among Blacks
– GET OUT OF ONE’S RINK to sow wild oats …Bk1903 colloq.
– GOOF to behave foolishly, and esp. in a time-wasting way …1929 sl., chiefly US
– GOOF AROUND to behave foolishly, and esp. in a time-wasting way …1929 sl., chiefly US
– GOOF OFF to behave foolishly, and esp. in a time-wasting way …1943 sl., chiefly US
– HACK to socialize idly; to gad or fool about; to waste time …1888 Amer. sl.
– HACK ABOUT to socialize; to fool about …1920s US college sl.
– HACK AROUND to socialize idly; to gad or fool about; to waste time …1923 US college sl.
– HACK OFF to idle; to loaf; to lounge; to go about aimlessly looking for distraction; to gad or fool about; to waste time …1920s US college sl.
– HORSE to indulge in rough jokes or horseplay; to fool around; hence, to waste time in trifling activity; also, to philander (now usually with ‘around’)…1900 US sl.
– JACKASS AROUND to fool about; to mess around; to waste time playing around …1927 colloq.
– JACK OFF to fool around, to do nothing …1940s US sl.
– JAG AROUND to fool around; to goof off …1968 Amer. dial.
– JAZZ AROUND to fool around …1917 Amer. dial.
– KICK THE GONG to fool around …1945 US sl.
– LALLIGAG, LALLYGAG to dawdle, to dally, to be idle; to waste time out of ineptitude or design; to fool about …1862 US sl.
– LOLLIGAG, LOLLYGAG to dawdle, to dally, to fool about; to be idle; to waste time out of ineptitude or malicious design …1862 US sl.
– LOON to fool about like a lunatic …1960s Brit. criminals’ sl.
– LOON ABOUT to fool about like a lunatic …1979 Brit. sl.
– LOSE TIME to waste time; to fool around …1967 Amer. dial.
– MEDDLE AROUND to fool around; to go about aimlessly looking for distraction …1968 Amer. dial.
– MESS to dawdle or putter; to fool around; to kid around, to tease …1966 Amer. dial.
– MESS WITH to become involved with; to use; to fool around with …19C US sl.
– MONK to tinker, trifle, or fool around; to tamper or interfere with surreptitiously …1889-90 Amer. sl.
– MONKEY to tinker, trifle, or fool around; to fritter away one’s time; usually used with ‘with’ …1877-78 Amer. sl.
– MONKEY AROUND to act without purpose; to play around …1884 Amer. colloq.
– MONKEY-FART AROUND to waste time; to fool about …a1970 Amer. sl.
– MUCK ABOUT to fool around; to trifle with …1856 sl.
– MUCK AROUND to fool around …1856 UK sl.
– NUTS to fool around …1941 Amer. sl.
– PISS-ARSE ABOUT to fool about; to waste time …c1920 army sl.
– SHUCK to be deceptive or evasive; to tell tall tales or lies; to fool around, to tease …1968 Amer. dial.
– SHUCK AND JIVE to act irresponsibly; to fool around …1970 Amer. dial.
– SILLY to act foolishly; to fool about …1877 chiefly Eng. dial.
 
FOOLED – adjectives
– EASY easily taken advantage of or imposed upon; easily fooled; credulous, gullible ..1698
fooled – peson 
– EASY MEAT someone who is easily fooled or seduced; a dupe; an easy target for deception …L19 sl.
  
FOOLERY – nouns (also see FOOLISHNESS)
– BARNEY nonsense, foolery …1868 Eng. dial.
– BARNEYING nonsense, foolery …Bk1898 Eng. dial.
– BAUBLE a childish or foolish matter of affair; a piece of childish foolery …1579
– BAUBLERY † childish foolery; trifling business …1583
– MONKEYSHINES foolish antics; embarrassing behaviour …1828 US sl.
– NIDGERY †* a small or worthless object; a trifle; a knickknack; a piece of foolery …1611 

FOOLHARDY – adjectives
– BALLSY courageous; daring; foolhardy …Bk2006 US sl.
– COLL-HARDY †* foolhardy; foolishly rash …1581
– DARESOME venturesome, foolhardy …1864 Eng. dial.
– DARING-HARDY † foolhardy, presumptuous, audacious …1593
– FLASH conceited, foolhardy, swaggering …Bk1892 Aust. sl.
– TEMEROUS rash, reckless, foolhardy …1461
– VENTURELESS venturesome, foolhardy, rash …Bk1905 Eng. dial.
foolhardy – nouns
– MOONRAKING the act of taking part in a foolhardy or unfruitful activity
foolhardy – person
– GIBBY – a reckless, foolhardy person …1968 US Black sl. 
foolhardy – verbs 
– DO DAGS to do something that the other person cannot do; to show off; to play foolhardy tricks …c1850 colloq.
– HAVE BRASS BALLS to be foolhardy, over-bold …Bk2002 Amer. sl.
– HAVE CAST-IRON BALLS to be foolhardy, over-bold …Bk2002 Amer. sl.
– PLAY WITH THE BULL to run needless risks; to be foolhardy …B1900 Eng. dial.
– TAKE A BEAR BY THE TOOTH to take foolhardy risks …1719
 
FOOLING ABOUT, FOOLING AROUND – adjectives
– DALLACKING fooling, play acting …2000 Ireland sl.
– GOOGY-GOOGY given to playing pranks; fooling around …1960s sl.
– PROMOSSING talking rubbish, playing the fool, mooning about …Bk1892 Aust. sl.
fooling about, fooling around – nouns 
– BUN-WORRY a jollification; a hilarious occasion; a fooling about …L19 Aust. & NZ sl.
 
FOOLISH – adjectives
– ABDERIAN given to incessant or continued laughter; inclined to foolish or excessive merriment; foolish, silly …18C
– ADOTED † grown silly, become foolish; infatuated …c1230
– AIR-HEADED foolish, unintelligent; frivolous; scatterbrained …1976 sl., orig. US
– ANSERINE stupid, foolish, silly …1607
ANSEROUS as stupid as a goose; silly, foolish …1826
– APE † foolish, silly …c1370
– ASS-BRAINED foolish; silly; witless …Bk1942 Amer. sl.
– BABOONISH foolish …E16
– BALD-HEADED stupid, foolish …1884 US Black sl.
– BALL-HEADED foolish …1884 Amer. dial.
– BARMY light-headed, foolish …1911 Sc. & Amer. dial.
– BARMY-BRAINED foolish, giddy, flighty; light-headed …1824 Sc.
– BARMY-FACED having a foolish or silly expression …1724 Sc.
– BEDAFT † foolish, stupid …1572
– BEDLAM belonging to a madhouse; mad, wild, ill-behaved, foolish …a1535
– BEDLAMITISH mad, foolish …1824
– BEGOYT foolish …1787 Sc.
– BENNISH foolish …17C sl.
– BENT AS A SCRUB TICK crazy; foolish …Bk1999 Aust. sl.
– BESOM-HEADED weak-minded, foolish, stupid …1864
– BIRD-BRAINED foolish, slow-witted, unintelligent, stupid …1922 sl.
– BLATHRIE nonsensical, foolish …Bk1911 Sc.
– BLETHER-HEADED foolish; noisy …Bk1911 Sc.
– BONE-HEADED foolish, slow-witted, unintelligent, stupid …1903 sl., orig. US
– BOOF-HEADED gullible; foolish; stupid …c1930 Aust. sl.
– BUFFLE-BRAINED stupid, foolish …1900 Amer. dial.
– BUGGY foolish, silly, witless, crazy, demented, insane, mentally deficient …1905 Amer. dial.
– BUGS foolish, silly, crazy, demented, insane, mentally deficient …1915 Amer. dial.
– CAKE stupid, foolish, daft …L19 sl.
– CAKEY stupid, foolish, daft; half-witted …L19 sl.
– CALFISH foolish …Bk1898 Eng. dial.
– CANG † foolish, silly …a1225
– CANGED † foolish, besotted …a1225
– CANK † foolish, silly …a1225
– CEMENT-HEADED stupid, foolish …1962 Amer. sl.
– CHANG † foolish, silly …a1225
– CHANK † foolish, silly …a1225
– CHOOKEE foolish, cowardly …1983 Amer. dial.
– CHUBBLE-HEADED silly, foolish …1892 Eng. dial.
– CHUCKLE-HEADED stupid, foolish …M18
– CLUELESS foolish, slow-witted, unintelligent, stupid …1943 sl.
– COCK-BRAINED having little judgement; foolish and light-headed; silly, giddy, rash, harebrained, thoughtless, flighty …1530
– COCKLE-BRAINED whimsical, eccentric, flighty, fanciful; foolish, chuckle-headed …1824 Sc.
– CORK-BRAINED foolish; silly; witless …Bk1942 Amer. sl.
– CORKY stupid, foolish …2000s US Black sl.
– CORKY-BRAINED silly, foolish …1699 sl.
– CRAZY WITH THE HEAT foolish; silly; witless …Bk1942 Amer. sl.
– CUCKOO foolish; silly; witless; slightly mad …Bk1942 Amer. colloq.
– DAFFADOWN DILLY silly, foolish, simple …1950s rhyming sl.
– DAFFEY eccentric; foolish …L19 sl.
– DAFFING playful, sportive, foolish …1724 Sc. 
– DAFFY daft; mad; crazy; silly; amusingly eccentric; foolish …1884 US sl.
– DAFFYDOWNDILLY (also as ‘daffydown dilly’) silly, foolish, simple …1950s rhyming sl.
– DAFFY-HEADED feather-brained; foolish; daft …1981 UK sl.
– DAFT silly, foolish, stupid …c1325 chiefly Sc. & N. Eng. dial.
– DAFT AS PANDON YATS silly, foolish …Bk1905 Eng. dial.
– DAFT-HEADED foolish …Bk1900 Eng. dial.
– DAFTISH somewhat silly, foolish, or stupid; somewhat slow of intellect, in some degree deranged …1825 Sc. & Eng. dial.
– DAFT-LIKE foolish, dull-witted, mad, absurd … 1790 Sc. & N. Eng. dial.
– DAFTLY weak-minded, foolish …1880 Sc.
– DAMFOOL damnably foolish; silly; stupid and irritating …c1895 colloq.
– DAMN-FOOL damnably foolish; silly; stupid and irritating …19C colloq.
– DAMNFOOLISH foolish; silly; witless …Bk1942 Amer. sl.
– DAMP foolish, stupid; crazy …L19 sl.
– DAMPHOOL damnably foolish …19C colloq.
– DAMPHOOLISH foolish; silly; witless …Bk1942 Amer. sl.
– DANDERING foolish, weak-minded, twaddling; incoherent, rambling in speech …Bk1900 Eng. dial.
– DATELESS stupefied, foolish, disordered in min, having the faculties failing through age …1685 Eng. dial.
– DAUPET silly, stupid, foolish, imbecile …1788 Sc.
– DAWPIT silly, stupid, foolish, imbecile …1788 Sc.
– DEDA simple, foolish, of inactive mind and body …B1900 Eng. dial.  
– DESIPIENT foolish, silly, childish, playful; playing the fool; idly trifling …1727
– DILEERIOUS extremely foolish …1891 Sc.
– DILL-BRAINED foolish …1975 Aust. sl.
– DILLY silly, foolish …1905 Aust. sl.
– DIM foolish, slow-witted, unintelligent, stupid …1892 sl.
– DIM-WITTED foolish, slow-witted, unintelligent, stupid …1940 sl.
– DING-A-LING foolish, crazy …1959 US sl.
– DINGBATS stupid, foolish …1950 Aust. sl.
– DINGY foolish, silly, witless, crazy; confused, mixed up …1911 Amer. dial.
– DIPPY foolish, unstable, silly; crazy, demented …1899 US sl.
– DIZZELL foolish; silly; witless …Bk1942 Amer. sl.
– DIZZY of a woman: silly, foolish …1878 Amer. dial.
– DIZZY-DOPEY foolish; silly; witless …Bk1942 Amer. sl.
– DIZZY-HEADED of a woman: silly, foolish …1965 Amer. dial.
– DIZZY IN THE HEAD of a woman: silly, foolish …1965 Amer. dial.
– DODDERING shaky, feeble, or infirm, as from old age; foolish, senile …Bk1942 colloq.
– DOOFY silly, foolish, eccentric …1980s US sl, chiefly juvenile usage
– DOPEY foolish, slow-witted, unintelligent, stupid …1903 sl.. orig. US
– DOPY foolish, slow-witted, unintelligent, stupid …1903 sl., orig. US
– DOTTY foolish; silly; witless …Bk1942 Amer. colloq.
– DOZEY foolish, slow-witted, unintelligent, stupid …1924 Brit. sl.
– DOZY foolish, slow-witted, unintelligent, stupid …1924 Brit. sl.
– DRONGO – foolish …1945 Aust. sl.
– DUMB foolish, slow-witted, unintelligent, stupid …1823 sl.
– DUMB-ASS stupid, foolish …1957 US sl.
– DUMB-ASSED foolish, slow-witted, unintelligent, stupid …1957 US sl.
– DUNCING † behaving like a dunce; stupid, foolish …1584
– DUNDERHEADED stupid, foolish, slow-witted …1692
– DUNDERING stupid, foolish; blundering …1840
– DUNT stupefied, numbed, dazed; stupid, foolish, dizzy, muddle-headed …1787 Eng. dial.
– DUSI † foolish, stupid …c1175
– DWEEBY foolish, inept, out of touch with current trends …1987 US sl.
– EGEDE † foolish …a1225
– EMPTY-BEANED foolish; silly; witless …Bk1942 Amer. sl.
– FARMER foolish …M19 sl.
– FAT-BRAINED foolish, stupid …L18 sl.
– FAT-HEADED foolish, stupid …c1510
– FATUANT †* behaving foolishly; foolish, silly …1641
– FATUOUS foolish, vacantly silly, stupid, besotted, infatuated …1633
– FEATHER-BRAINED foolish, giddy, light-headed …1820
– FEATHER-MINDED foolish; silly; witless …Bk1942 Amer. sl.
– FEATHER-PATED foolish, giddy, light-headed, silly …1820
– FIDDLE-BRAINED † foolish, frivolous …B1900
– FISH foolish, stupid …1980 Amer. dial.
– FLOCK-PATED † silly, stupid, foolish; giddy; having a head or brains like wool …?1640
– FOLLY-FOO very foolish …1898 Sc.
– FOND AS A BESOM very foolish; apt to commit absurd mistakes …Bk1898 Eng. dial.
– FOOL foolish …Bk1974 Amer. colloq.
– FOOL-HEADED foolish; silly; witless …1914 Amer. sl.
– FOOTY foolish, simple …19C sl.
– FOPPERLY † silly, foolish …1599
– FURIOUS † foolish, absurd …1526
– FUZZY foolish; silly; witless …Bk1942 Amer. sl.
– GABY foolish, idiotic …1874 Eng. dial.
– GAELIC foolish, ingenuous, naive …1910 Sc.
– GAFFLED silly, foolish …Bk1900 Eng. dial.
– GAGA foolish; silly; witless; sentimental about, infatuated …1917 sl.
– GAIPY rash, foolish, imprudent …1929 Sc.
– GALEERY foolish …20C Irish sl.
– GAMALEERIE foolish …1825 Sc.
– GAMAREERIE foolish …1880 Sc.
– GAMMEREERIE foolish …1880 Sc.
– GANDER-FACED foolish-looking …L19 sl.
– GANDERISH foolish; silly; witless …Bk1942 Amer. sl.
– GAPING-MOUTHED gaping, foolish, idiotic …Bk1900 Eng. dial.  
– GAPPY rash, foolish, imprudent …1929 Sc.
– GAUFFIN light-headed, foolish, thoughtless, giddy …1810 Sc.
– GAWBY foolish, idiotic; ill-mannered, uncouth …1874 Eng. dial.
– GEND † foolish, simple …a1500 Sc.
– GIDDISH †* giddy, fickle, foolish …1566
– GIGGISH lively, flighty, wanton, trifling, silly, foolish …1523
– GLAIKET, GLAIKIT stupid, careless, foolish …1889 Sc.
– GONNER-NOPED thoughtless, foolish …Bk1900 Eng. dial.
– GOOFY silly, foolish …1910s sl.
– GOOFY-ASS silly, foolish …1910s sl.
– GOO-GOO foolish; mawkish; sentimental …1910s US sl.
– GOOPISH foolish; silly; witless …Bk1942 Amer. sl.
– GOOPY foolish; silly; witless …Bk1942 Amer. sl.
– GOOSEY foolish, stupid. silly, light-headed, witless …1919 Amer. dial.
– GORMLESS foolish, slow-witted, unintelligent, stupid …c1746 sl.
– GUCKED † foolish, silly …c1450 chiefly Sc.
– GUMP-HEADED stupid, foolish, awkward …1722 Amer. dial.
– GUPPY foolish, stupid, silly …c1930 sl.
– GYPED, GYPIT silly, foolish, idiotic …1804 Sc.
– HAGGIS-HEADED soft-headed, foolish, stupid …1715 Sc.
– HALF-BAKED foolish, silly, weak of intellect;  raw, inexperienced …1897 Eng. dial.
– HALF-BAKED foolish, silly, half-witted, weak of intellect;  raw, inexperienced …1855 Eng. dial.
– HALF-BAPTIZED foolish, silly, weak of intellect …1795 Eng. dial.
– HALF-GONE foolish, silly, weak of intellect …1893 Eng. dial.
– HALF RIGHT foolish, silly, weak of intellect …1866 Eng. dial.
– HALF-ROCKED half-witted, silly, foolish, oafish …1869 Eng. dial.
– HALF-SAVED half-witted, foolish, silly, weak of intellect …1871 Eng. dial.
– HALF-SCRAPED foolish, silly, weak of intellect …Bk1905 Eng. dial.
– HALF-SHAKED foolish, silly, weak of intellect …Bk1905 Eng. dial.
– HALF-SHANNY foolish, silly, weak of intellect …Bk1905 Eng. dial.
– HALF-SHAVED foolish, silly, weak of intellect …Bk1905 Eng. dial.
– HALF-SOAKED foolish, silly, weak of intellect …1895 Eng. dial.
– HALF-STRAIN foolish, silly, weak of intellect …1873 Eng. dial.
– HALF-STRAINED foolish, silly, weak of intellect …Bk1905 Eng. dial.
– HALF THERE foolish, silly, weak of intellect …Bk1905 Eng. dial.
– HALF-THICK foolish, silly, weak of intellect …Bk1905 Eng. dial.
– HALF-WITTED not having all one’s wits; imbecile; foolish; stupid …1712
– HALLACHIN noisy, foolish …Bk1905 Sc.
– HALLOPIN unsteady, unsettled, foolish …Bk1905 Sc.
– HALOKIT giddy, thoughtless, foolish, crazy …1724 Sc.
– HARISH † of the nature of a hare; mad, foolish …1552
– HASK foolish; not quite right in the head …Bk1902 Eng. dial.
– HAUVING simple-witted, foolish, clownish …Bk1902 Eng. dial.
– HAUVISH simple-witted, foolish, clownish …Bk1902 Eng. dial.
– HAVEREL foolish, silly, half-witted, nonsensical; talking foolishly …1685 Sc. & N. Eng. dial.
– HAVERIL foolish, silly, nonsensical; talking foolishly …1685 Sc. & N. Eng. dial.
– HAWKED stupid, foolish …1790 Sc.
– HEARTLESS † without understanding; foolish …1382
– HEN-HEADED brainless, foolish …1700 Eng. & Amer. dial.
– HEN-MINDED brainless, flighty, capricious; foolish, silly, witless …1892 Amer. dial.
– HOLLOW-HEADED foolish, silly …B1900 Eng. dial.
– IDLE † void of meaning or sense; foolish, silly, incoherent …1548
– IDLE-HEADED † of little understanding or intellect; silly, foolish; crazy …1598
– INFIRM silly, foolish …1890 Eng. dial.
– INSIPIENT void of wisdom, understanding, or intellect; unwise, foolish, stupid …1528
– IVORY-DOMED stupid, foolish …1932 US sl.
– JINGLE-BRAINED foolish; silly; witless …Bk1942 Amer. sl.
– KANG † foolish, silly …a1225
– KNOCK-SOFTLY stupid, foolish …1887 Eng. dial.
– LACK-THOUGHT wanting or lacking thought; foolish, stupid, vacant …1829
– LACK-WIT foolish, idiotic, or simple-minded …1735
– LAMB-BRAINED foolish …1998 NZ sl.
– LAME-BRAINED foolish, slow-witted, unintelligent, stupid …1929 sl., chiefly US
– LEAN-WITTED silly, stupid, foolish; having little sense or shrewdness …1593
– LEARY dazed, bewildered; foolish, half-witted …1911 Amer. dial.
– LEATHER-HEADED stupid, foolish, slow-witted …a1668
– LEFT-WITTED dull, stupid, foolish, silly …1616
– LEWD † foolish, unskilful, bungling; ill-bred, ill-mannered …c1380
– LOLO insane, crazy; foolish, dull, stupid …1938 Hawaii
– LOONY foolish; silly; witless …Bk1942 Amer. sl.
– LUNATIC madly foolish, frantic, idiotic …1571
– LUNCH stupid, foolish, crazy …1960s sl.
– LUNKHEADED slow-witted, foolish …L19 sl.
– LUNY foolish; silly; witless …Bk1942 Amer. sl.
– MAD AS A MAGGOT, AS very crazy, extremely eccentric; hence, egregiously foolish …20C NZ sl.
– MADDED † mad, foolish …Bk1905 Sc.
– MADDLING foolish, silly, flighty; confused …Bk1905 Eng, dial.
– MAFFLING blundering, clumsy, foolish, stupid …Bk1905 Eng. dial.
– MARMOSETICAL † characteristic of a marmoset; apishly foolish …1630
– MAWMISH † foolish, silly, idle …B1900
– MAZLING stupid, foolish, confused …1885 Eng. dial.
– MEAT-HEADED foolish, slow-witted, unintelligent, stupid …1949 sl., chiefly US
– MENSELESS thoughtless, silly, foolish; senseless …1809 Sc.
– MOOKY foolish, contemptible, ineffectual …1967 US sl.
– MOONY crazy; foolish; silly, esp. in demonstrating affection …Bk1942 sl.
– MOPISH † foolish, silly
– MUDDLE-BRAINED confused, foolish, simple …M18
– MUDDLE-HEADED confused, foolish, simple …M18
– MUGGY foolish, in the manner of a mug …1997 UK sl.
– MULLET-HEADED foolish, slow-witted, unintelligent, stupid …1857 US sl.
– MUSH-FACED stupid, foolish …1910s sl.
– MUTTON-HEADED foolish, slow-witted, unintelligent, stupid …1768 sl.
– NANNY-CRATTY foolish, weak-minded, childish; of small account; generally used of persons, but also of a conversation or work …Bk1905 Eng. dial.
– NARROW stupid, foolish …Bk1902 sl.
– NEDDYISH silly, foolish …Bk1905 Eng. dial.
– NENA simple, foolish …Bk1905 Eng. dial.
– NERTS crazy, foolish …1910s US sl.
– NERTZ crazy, foolish …1910s US sl.
– NICKIN foolish, simple …L17 sl.
– NIKEY foolish, simple …L17 sl.
– NIKIN foolish, simple …L17 sl.
– NINNY-NONNY stupid, foolish, weak-minded, childish …Bk1865 Eng. dial.
– NIPPERTY-TIPPERTY silly, frivolous, foolish, light-headed …1817 Sc. 
– NISEY † foolish, dull …1709
– NIZY foolish, dull …L17 sl.
– NIZZIE foolish, dull …L17 sl.
– OAFING stupid, foolish …Bk1905 Eng. dial.
– OAF-ROCK’D half-witted, stupid, foolish, silly …Bk1905 Eng. dial.
– OFF mad, very foolish …L19 sl.
– OFF ONE’S KADOOVA insane, foolish …Bk1999 Aust. sl.
– OFF ONE’S NUT crazy; foolish …Aust. sl.
– PAPER-SCULLED. foolish, simple …L17 sl.
– PAPER-SKULLED foolish, simple …L17 sl.
– PAPPY-SHOW foolish, ridiculous …L19 W. Indies
– PEA-BRAINED foolish, slow-witted, unintelligent, stupid …1950 sl.
– POPPY-SHOW foolish, ridiculous …L19 W. Indies
– PRECIOUS FOOLISH foolish; silly; witless …Bk1942 Amer. sl.
– PRIZE SAPPY foolish; silly; witless …Bk1942 Amer. sl.
– PRUNY foolish; silly; witless …Bk1942 Amer. sl.
– PUERILE childishly foolish; immature or trivial …17C
– PUGGLED given to foolish behaviour …1985 Sc. sl.
– PUPPY-SHOW foolish, ridiculous …L19 W. Indies
– RADGE of an idea or situation: foolish, silly, absurd …1961 sl.
– RADGY of an idea or situation: foolish, absurd …1990s sl.
– RAFFLE idle; foolish …Bk19C Eng. dial.
– RALPH weak, silly, foolish …Bk1905 Eng. dial.
– RATTLE-BEANED foolish; silly; witless …Bk1942 Amer. sl.
– RATTLE-BRAINED talkative; flighty; harebrained; silly; stupid; prone to confusion; foolish; unable to concentrate …1868 Sc.
– RATTLED confused; foolish; silly; confused by excitement …20C Amer. sl.
– RATTLE-HEADED empty-headed, stupid; foolish and noisy; talkative, chattering, giddy, flighty, hare-brained …1647
​- ROCKED IN A STONE KITCHEN said of a fool, his brains having been disordered by the jumbling of his cradle …1809
– SACKLESS lacking common sense; silly; foolish; stupid; thoughtless; useless, awkward …1878 Sc. & Eng. dial.
– SAGGER-YEDDED stupid, foolish …Bk1904 Eng. dial.
– SAKELESS without sense or gumption; silly, foolish, lacking drive or energy, sloppy, careless …1820 Sc.
– SAMMY foolish, dull …E19 sl.
– SANNOCKING silly, foolish …1893 Eng. dial.
– SAP-HEAD foolish …M17 sl.
– SAP-HEADED foolish, silly, stupid, witless …1665
– SAPLESS foolish, silly, witless …Bk1904 Eng. dial.
– SAPPY foolish, silly, witless …1670
– SAPPY-HEADED simple-minded, silly, foolish …1881
– SART foolish, imbecile, daft …1885 Eng. dial.
– SAUFFLING foolish, weak …Bk1904 Eng. dial.
– SAUMPY weak-minded, foolish …1856 Eng. dial.
– SAWNEY foolish, stupid, weak; foolishly sentimental …1894 Eng. dial.
– SCRAMBLE-BRAIN foolish; silly; witless …Bk1942 Amer. sl.
– SCRANNY crazy, mad, distracted; simple, foolish; bewildered …Bk1904 Eng. dial.
– SHALLOW-BRAINED † having no depth of intellect or understanding; foolish, empty-headed
– SHALLOW-PATED having no depth of intellect or understanding; foolish, empty-headed …arch.
– SHAY-BRAINED foolish, silly …1806 Eng. dial.
– SHORT OF NUMBERS IN THE UPPER HOUSE foolish, stupid …Bk1999 Aust. sl.
– SICK OF THE SIMPLES foolish …18C colloq
– SIL(L) foolish …1930s sl.
– SILLY-ARSE stupid, foolish …1910s sl., chiefly US
– SILLY AS A WET HEN extremely foolish, silly, or stupid …1980s NZ sl.
– SILLY AS A WHEEL extremely foolish,  silly or stupid …1950s Aust. sl.
– SILLY-ASS stupid, foolish …1910s sl., chiefly US
– SILLY-ASSED stupid, foolish …1910s sl., chiefly US
– SILLY-BORN stupid, foolish …1940s sl.
– SILLYISH * somewhat foolish …1761
– SIMP foolish …2000 US sl.
– SIMPY foolish, gullible …1940s sl.
– SLAP-HAPPY foolish; silly; witless …Bk1942 Amer. sl.
– SLAPPY foolish; silly; witless …Bk1942 Amer. sl.
– SLUGGY foolish; silly; witless …Bk1942 Amer. sl.
– SLUG-NUTTY foolish; silly; witless …Bk1942 Amer. sl.
– SNEPE foolish, silly …a1250
– SPOONY foolish, silly …1805 colloq.
– SQUIRISH foolish …L18 sl.
– STEAMBOATS foolish, silly …2000 UK sl.
– STULTILOQUENT * talking foolishly; given to silly talk; babbling …1845
– STULTITIOUS † foolish, ridiculous …1547
– STULTY †* foolish, stupid …1387-8
– TABETLESS heedless, foolish, silly …1786 Sc.
– TACOU foolish, stupid …20C W. Indies sl.
– TAFFEREL thoughtless, foolish, giddy; also, ill-dressed …1822 Sc.
– TAIVERT stupid, foolish, muddle-headed, slow-witted, half-witted …1818 Sc.
– TAKE YOUR PICK stupid, foolish …1998 UK rhyming sl. for ‘thick’
– TAPETLESS heedless, foolish, silly …1786 Sc.
– TAPIE foolish, awkward, slovenly, foolishly thoughtless …1706 Sc. & N. Eng. dial.
– TAUPIE foolish, awkward, slovenly, ill-conditioned; foolishly thoughtless …1706 Sc. & N. Eng. dial.
– TAUPY foolish, awkward, slovenly, ill-conditioned; tawdry …1823 Sc.
– TAWPIE foolish, awkward, slovenly, ill-conditioned, foolishly thoughtless; tawdry …1706 Sc. & N. Eng. dial.
– TAWPY foolish, awkward, slovenly, ill-conditioned; tawdry …1823 Sc.
– TEWITISH wild, foolish …Bk1905 Eng. dial.
– THICK foolish, slow-witted, unintelligent, stupid …a1800 sl.
– TIN-EARED foolish …1930s sl.
– TITTERY foolish; silly; witless …Bk1942 Amer. sl.
– TOMFOOL extremely foolish
– TUNKLE-HEADED foolish, stupid …1903 Amer. dial.
– UNASINOUS agreeing in stupidity; displaying ignorance or foolishness by all …1656
​- UP AGAINST THE WALL foolish, stupid …1960s US college sl.
– VAIN † of persons: devoid of sense or wisdom; foolish, silly, thoughtless; of an idle or futile nature or disposition …1390 rare or obs.
– VOLAGE giddy, foolish; fickle, inconstant, inconsiderate …a1366
– VOOM-VOOM foolish; silly; witless …Bk1942 Amer. sl.
– WANWITTY † foolish …a1500
– WOODENTOP foolish …1983 UK sl.
– WRONG silly, foolish; extremely eccentric, or slightly mad …1920s Aust. sl.
– YAPPY foolish, soft; idiotic …M19 sl.
– YAWNEY simple, foolish …19C sl.
– ZATHY simple, foolish …Bk1904 Eng. dial.
foolish – nouns
– IDIOTICALS foolish things; nonsense; cheap, trashy news …1826 Sc.
– MUG’S GAME a thankless task; a useless, foolish, or unprofitable activity …1900
foolish – verbs
– ACT THE ANGORA to behave foolishly …Bk1999 Aust. sl.
– COME DOWN IN THE LAST SHOWER to be inexperienced, foolish, or gullible; chiefly used in negative contexts …1883 Aust. & NZ colloq.
– HAVE BIRD DROPPINGS FOR BRAINS to be extremely stupid or foolish …1979
– HAVE BRICKDUST FOR BRAINS to be extremely stupid or foolish …1800
– HAVE COTTON-BATTING FOR BRAINS to be extremely stupid or foolish …1901
– HAVE SAWDUST FOR BRAINS to be extremely stupid or foolish …1833
– HAVE SHIT FOR BRAINS to be extremely stupid or foolish …1960 sl., orig. US
– HAVE SOUP FOR BRAINS to be extremely stupid or foolish …1979
– JUMP SMART to act in a foolishly ‘clever’ manner …1970s US Black sl.
– MAKE AN ASS OF SOMEONE to cause someone to appear absurd or foolish …1548
– MAKE A PROPER GALAH OF ONESELF to behave foolishly …Bk1999 Aust. sl.
– RAIN DOWN IN THE LAST SHOWER to be inexperienced, foolish, or gullible; chiefly used in negative contexts …1843 Aust. & NZ colloq.
– TURN A PERSON”S BRAIN to make a person dizzy or giddy; to disturb a person’s mental balance, to make a person foolish or rash …c1440
foolish – phrases 
– MORE F THAN R ‘more fool than rogue’; originally and chiefly used of a servant …M19 sl.
– YOU’RE OUT OF YOUR TINY MIND you’re crazy, foolish, mad …1970 UK sl.
 
FOOLISHLY – adverbs
– CANGLICHE † foolishly …a1225
– DAFFY-LIKE foolishly, like an idiot …Bk1900 Eng. dial.
– DAFTLY foolishly …1787 Sc.
– DAWKINLY stupidly, foolishly …1750 Eng. dial.
– GOOK-EYED stupidly, foolishly, vacantly …1950s US sl.
– HEARTLESSLY † foolishly …1611
– LEWDLY † ignorantly; foolishly …c1380
– LIKE A MONKEY TRYING TO BUGGER A FOOTBALL very clumsy; foolishly …1965 Amer. sl.
– LIKE A MONKEY TRYING TO FUCK A FOOTBALL very clumsy; foolishly …1981 Amer. sl.
– LOOBILY foolishly …M14
– MAZE-LIKE stupidly, foolishly; like a madman …1866 Eng. dial.
– OAFLY foolishly, absurdly …Bk1905 Eng. dial.
– VAINLY † foolishly, senselessly, thoughtlessly …1588
 
FOOLISHNESS – nouns (also see FOOLERY)
– ADDLE-HEADEDNESS fatuity, foolishness, folly …1835
– BALONUS pretentious nonsense; humbug; foolishness …1929 Amer. sl.
– BLADRY foolishness, deception …Bk1911 Sc.
– BLETHERIE foolishness; deception …Bk1911 Sc.
– BLUTE a bad or foolish action …Bk1911 Sc.
– CACA nonsense, rubbish; foolishness …1970s US sl.
– CHAFF nonsense, humbug, foolishness, ridicule; small, unimportant things or acts …1859 Amer. dial.
– COD-ACTING foolish behaviour …20C sl., orig. Irish
– DAFF fun, frolic; playing the fool …1737 Sc.
– DAFFERY † folly, foolishness, gaiety, sportiveness; thoughtlessness …1768 Sc.
– DAFFING fooling, folly …1535
– DAFFLIN fooling, merriment …Bk1900 Eng. dial.
– DAFFRY † folly, foolishness; thoughtlessness …1768 Sc.
– DAFTNESS foolishness, dullness, madness …1552 chiefly Sc. & Eng, dial.
– DUNDERHEADISM foolishness, stupidity …1836
– DUSILEC † foolishness; folly …a1225
– DUSISCHIP † foolishness; folly …a1225
– FADOODLE †* something foolish or ridiculous; nonsense; a mere nothing; a useless trifle …a1670
– FANDANGLE stupidity, foolishness …1940s W. Indies sl.
– FARADIDDLE nonsense, foolishness …1944 Amer. dial.
– FATUOUSNESS besotted foolishness, stupidity, infatuation; imbecility …1874
– FIGGLE-FAGGLE conduct which is foolish, ludicrous, or unbecoming; silly or trifling conduct; ridiculous behaviour …19C Sc.
– FLUMMYDIDDLE foolishness, nonsense …1903 Amer. dial.
– FOLABILITY †* foolishness, folly …a1529 
– GOOFINESS foolishness …1910s sl.
– GUCKRY † foolishness, folly …1596 Sc.
– GYPERY foolish or silly behaviour …1832 Sc.
– GYPITNESS foolishness, silliness …1804 Sc.
– HAIVER a piece of folly or nonsense; a whim, a piece of foolishness …1793 Sc.
– HAPPY HORSESHIT foolish stuff …1971 US sl., esp. military usage
– HAVRELISM the habit of behaving in foolish, harum-scarum fashion …1826 Sc.
– IDLENESS †* light-headedness, imbecility; delirium; also, folly, foolishness, silliness …a1536
– JACKASSISM action or behaviour characteristic of a jackass or fool; foolishness, stupidity …1817
– JACKASSNESS the quality of being a jackass or fool; foolishness, stupidity …1803
– LALLYGAG foolishness, nonsense; idle talk, chatter …1862 Amer. dial.
– LEATHER-HEADEDNESS stupidity; foolishness …1879 Amer. dial.
– LEG-PULL the act of deceiving or fooling someone …1915 Amer. sl.
– LEWDHEDE †* ignorance; want of skill, knowledge, or good-breeding; foolishness …1401
– LEWDNESS † ignorance; want of skill, knowledge, or good-breeding; foolishness …1362
– LOLLYGAG foolishness, nonsense; idle talk, chatter …1862 Amer. dial.
– MAZERY nonsense, foolery; madness …1897 Eng. dial.
– MIFF-MAFF nonsense; foolishness …1858 Eng. dial.
– MIFKY-PIFKY foolishness or mischief, esp. of a romantic or sexual nature; sexual activity; hanky panky …1985 Amer. jocular
– MONKEY BUSINESS foolishness; also, underhand actions or trickery; misbehaviour …1883 Amer. sl.
– MONKEY CAPERS monkey business …1846 Amer. sl.
– MONKEY PLAY foolishness; also, underhand actions or trickery; misbehaviour …1953 Amer. sl.
– MONKEY-SHINES foolish behaviour …c1832 US sl.
– MONKEY TRICKS foolish behaviour …1653 sl.
– MONKEY WORK foolishness; also, underhand actions or trickery; misbehaviour …1942 Amer. sl.
– MOOFKY-POOFKY foolishness or mischief, esp. of a romantic or sexual nature; sexual activity; hanky panky …1994 Amer. jocular
– MOOFTY-POOFTY foolishness or mischief, esp. of a romantic or sexual nature; sexual activity; hanky panky …1996 Amer. jocular
– MOONSHINE foolish talk or thought
– NODDARY †* a foolish action, foolishness …1647
– NOISE nonsensical talk; hence, foolishness …1871 Amer. sl.
– OKEY-DOKE foolishness; stupidity; pretense …1969 sl., esp. Black usage
– PAPPY SHOW foolishness, showing off …L19 W. Indies
– POPPY SHOW foolishness, showing off; one who makes a stupid exhibition of themselves …L19 W. Indies
– PUERILITY the state or quality of being a child; the quality of being childish, foolish, or trivial …1425
– PUPPY SHOW foolishness, showing off; one who makes a stupid exhibition of themselves …L19 W. Indies
– RAFF idle ways; foolishness …Bk19C Eng. dial.
– RAGE † madness, folly, rashness; an instance of this; a foolish act …a1300
– SAPHEADISM foolishness …L18 sl.
– SAPPINESS foolishness, folly …Bk1914 colloq.
– SCHMOOFKY-FOOFKY foolishness or mischief, esp. of a romantic or sexual nature; sexual activity; hanky panky …1997 Amer. jocular
– SIMPLES † foolish or silly behaviour or conduct; foolishness, folly …1648 obs. exc. Eng. dial.
– SIMPLESSE † deficiency in knowledge or learning; ignorance; also, lack of mental acuteness, intellectual weakness, foolishness …c1400 obs. exc. arch.
– SOTTERY † a piece of foolishness or folly …1598
– THING-A-ME-TOY a foolish act …B1900 Eng. dial.
– TRUCK nonsense, foolishness …1913 Amer. dial.
– VAINNESS † foolishness; stupidity …1591
– VANITY † the quality of being foolish or of holding erroneous opinions …c1386
– WANWIT † lack of wit, foolishness …a1400 chiefly Sc.
– WOOBLES feeblemindedness, foolishness, idiocy …1933 Amer. dial.
– YORNEYISHNESS simplicity, foolishness, half-wittedness …1885 Eng. dial.
– YORNEYISM simplicity, foolishness, half-wittedness …1884 Eng. dial. 
foolishness – verbs
– COME OFF THE GRASS to stop talking foolishness …a1891 US sl.
foolishness – phrases 
– BORE FOR THE SIMPLES refers to a stupid person; the idea is that a hole in the skull might let some of the foolishness out …1916 Amer. dial.