UNRELIABLE
ADJECTIVES
– ALL ENDS AND SIDES unreliable, scatterbrained …Bk1898 Eng. dial.
– FALLIBLE of rules, opinions, arguments, etc.: liable to be erroneous, unreliable …a1420
– FLAKY inattentive, distracted, unreliable …1959 US sl.
– FLY-BY-NIGHT unreliable or untrustworthy, esp. in finance …colloq.
– KAFFIR of low quality; bad; inferior; unsatisfactory, unreliable …1934 S. Afr. sl., offensive
– LOOSE IN THE HAFT unstable, unreliable ….c1325 obs.
– MEXICAN of time or events: late, slow, unreliable …1968
– ODDBALL disorganized; prone to blunder; unreliable …c1945 sl.
– RAGGLISH of persons: wild, unreliable, undisciplined, rough, boisterous …1866 Sc.
– SHADY uncertain, unreliable …M19 sl., orig. university
– SHONKY unreliable, dishonest, ‘crooked’ …1970 Aust. sl.
– SILLY AS A TWO-BOB WATCH unreliable; dizzy, crazy …1954 Aust. sl.
– SILLY AS A WET HEN unreliable; dizzy, crazy …Bk1999 Aust. sl.
– TICKLE not to be depended on; uncertain; unreliable; changeable; inconstant; capricious; fickle …a1300 obs. exc. Eng. dial.
– UNASSURE unreliable …1531 obs.
– UNCANNY unreliable, not to be trusted …1639 obs.
– WACKY incorrect, unreliable; eccentric …1930s sl., orig. US
– WONKY unsound or unreliable …1925 UK sl.
NOUNS
– ABORTION an object, esp. a machine, of ludicrous or ungainly appearance; also, an unreliable mechanical device that provokes anger by breaking down …1943 Amer. sl.
– QUEER PAPER something dubious or unreliable …M19 sl.
NOUNS, PERSON
– BAD EGG a dishonest, unreliable, and wicked person …Bk1980 Amer. sl.
– BEAT a generally unreliable person, esp. one who fails to pay their debts, spec. hotel bills …1879 US sl.
– BROKEN REED an unreliable or weak person …Bk1999
– BROKEN STICK somebody or something unreliable, undependable, or inadequate …1946 Amer. dial.
– BUG an unreliable person; a cheat …1885 Amer. dial.
– CRANK a mentally unstable person; an unreliable, unpredictable person; a person who is obsessed by a single topic or hobby …1833 US sl.
– EASTIE-WASTIE an unreliable or unstable person; one on whose word there can be no dependence …1808 Sc. obs.
– FLAKE a crazy, eccentric, or unreliable person …1959 sl., chiefly US
– FLAPPY-TONGUE one whose word cannot be relied on …Bk1900 Eng. dial.
– FLY BULL an eccentric, unusual, unreliable person …Bk1974 Amer. sl.
– FLY COP an eccentric, unusual, unreliable person …Bk1974 Amer. sl.
– FLY DICK an eccentric, unusual, unreliable person …Bk1974 Amer. sl.
– FLY MUG an eccentric, unusual, unreliable person …Bk1974 Amer. sl.
– GAMMONER a person who talks volubly or flatteringly, esp. so as to deceive or cajoler another into a particular course of action; a talkative, unreliable person; a liar; one who tells deceitful tales …1819
– GOOSE-CAP a silly person; a harum-scarum, unreliable girl … 1589 obs. exc. Eng. & Amer. dial.
– NING-NANG a worthless or troublesome person; an unreliable person; a silly or stupid person; a fool …1832 Eng. dial.
– PIKER one who can’t be depended upon …Bk1913-17 Amer. dial.
– SKITE an unreliable or extravagant person …1995 Amer. dial.
– WAFFLER an unsteady person; one not to be depended on; a waverer …1889 Eng. dial.
– WANKLE a person not to be relied upon …Bk1905 Eng. dial.
– WIND-EGG a noisy, unreliable person …Bk1905 Eng. dial.
– WUSS BAG a weakling; someone who cannot be depended on …1970s sl., orig. US
– WUSSETTE a weakling; someone who cannot be depended on …1970s sl., orig. US
– WUSSY a weak, timid, passive person; someone who cannot be depended on …1960s US sl.
PHRASES
– AS MANY FACES AS A CHURCHYARD CLOCK used of anyone seen as duplicitous or unreliable …20C
VERBS
– FALSE of a thing: to prove unreliable, to fail, to give way …c1205 obs.
Lexicophilia 