Thesaurus.com Dictionary.com

without rehearsal

ADVERB

ad-lib

Synonyms

STRONG

impromptu

WEAK

extemporaneously extempore off the cuff off the top of one's head spontaneously without preparation

Antonyms

WEAK

deliberately planned prepared rehearsed written

From Roget's 21st Century Thesaurus, Third Edition Copyright © 2013 by the Philip Lief Group.