4
spontaneously(adverb, improv, extemporaneously)
4
stopgap(adjective, helping)
4
unarranged(adjective, spontaneous, unprepared, unplanned, unrehearsed)
4
uncontrived(adjective, simple, natural, casual, impulsive)
4
uncontrolled(adjective, simple, natural, casual, impulsive)
4
unexpected(adjective, chance, unqualified, vulnerable, spontaneous)
3
extemporarily
3
fake(adjective, adverb, free, casual, impulsive)
3
ill-considered(adjective, impulsive, unqualified, unprepared, unsuspecting)
3
rough-and-ready(adjective, unprepared)
3
sudden(adjective, unexpected, quickly)
3
undevised(adjective, unprepared)
2
by ear(expression, adverb, free, offhand, unrehearsed)
2
cold(adjective, unqualified, unsuspecting, unready)
2
free(adjective, simple, fake, natural, casual)
2
from the hip(expression, adjective, idiom, simple, natural)
2
hurried
2
improvisatory(free, casual, impulsive, spontaneous, unprepared)
2
jury-rigged
2
made-up(adjective, adverb, free, impulsive, spontaneous)
10 years ago|12k views|share |citing 
APASmart Define. (2016). impromptu thesaurus. Retrieved September 21, 2026, from https://smartdefine.org/impromptu/thesaurus/synonyms
ChicagoSmart Define. 2016. "impromptu thesaurus" https://smartdefine.org/impromptu/thesaurus/synonyms (accessed September 21, 2026).
HarvardSmart Define 2016, impromptu thesaurus, Smart Define, viewed 21 September, 2026, <https://smartdefine.org/impromptu/thesaurus/synonyms>.
MLASmart Define. "impromptu thesaurus" 28 January 2016. Web. 21 September 2026. <https://smartdefine.org/impromptu/thesaurus/synonyms>