See ad-lib in Webster's New World Roget's A-Z Thesaurus II
verb
To compose or recite without preparation:
extemporize, fake, improvise, make up. Idiom: wing it. See planned, prepared
noun
Something improvised:
extemporization, impromptu, improvisation. See planned, prepared
adjective
Spoken, performed, or composed with little or no preparation or forethought:
extemporaneous, extemporary, extempore, impromptu, improvised, offhand, snap, spur-of-the-moment, unrehearsed. (Informal) off-the-cuff. See prepared
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