AD-LIB
NOUNS
► GAG an ad-lib remark → M19 sl.
NOUNS, PERSON
► GAGGER a person who ad-libs; a joker; in a theatrical context, esp. of comedians → 1841 UK sl.
VERBS
► FAKE IT to ad lib, to improvise words or music → 1889 sl., orig. theatrical usage
► GAG to ad-lib → M19 sl.
► IMPROVISATE to ad lib, to speak extempore → 1838
► IMPROVISATORIZE to ad lib, to improvise, to speak extempore → 1828
Lexicophilia 