Open English Wordnet
Nouns
Verbs
(v)improvise, improvize, ad-lib, extemporize, extemporiseperform without preparation“he extemporized a speech at the wedding”
Adjectives
(s)ad-lib, extemporaneous, extemporary, extempore, impromptu, offhand, offhanded, off-the-cuff, unrehearsedwith little or no preparation or forethought“his ad-lib comments showed poor judgment”, “an extemporaneous piano recital”, “an extemporary lecture”, “an extempore skit”, “an impromptu speech”, “offhand excuses”, “trying to sound offhanded and reassuring”, “an off-the-cuff toast”, “a few unrehearsed comments”
(s)ad-lib, spontaneous, unwrittensaid or done without having been planned or written in advance“he made a few ad-lib remarks”