2
unconscious(adjective, simple, natural, casual, impulsive)
2
unconsidered(noun, thoughtless, impetuous, unwary)
2
undesigned(adjective, unplanned, unintentional, accidental, inadvertent)
2
unintended(adjective, chance, unplanned, unintentional, accidental)
2
unpredictable(noun, thoughtless, impetuous, unwary)
2
voluntary(adjective, simple, natural, casual, impulsive)
1
accidental(chance, unplanned, unpremeditated, inadvertent)
1
according to pleasure(expression, idiom, adverb, impulsive, extemporize)
1
aimless(unplanned, accidental, inadvertent)
1
as one thinks best(expression, idiom, adverb, impulsive, extemporize)
1
as one wishes(expression, idiom, adverb, impulsive, extemporize)
1
at will(expression, adverb, informal, impulsive, extemporize)
1
autoschediastic(adjective, free, casual, impulsive, spontaneous)
1
break loose(expression, adjective, simple, natural, casual)
1
caught napping
1
caught off balance(expression, idiom)
1
caught short
1
chance(unplanned, accidental, unpremeditated, inadvertent)
1
dashed off(expression, fake, unprepared, unplanned, unrehearsed)
1
devil-may-care(noun, thoughtless, impetuous, unwary)
11 years ago|9.3k views|share |citing 
APASmart Define. (2015). extemporaneous thesaurus. Retrieved September 28, 2026, from https://smartdefine.org/extemporaneous/thesaurus/synonyms
ChicagoSmart Define. 2015. "extemporaneous thesaurus" https://smartdefine.org/extemporaneous/thesaurus/synonyms (accessed September 28, 2026).
HarvardSmart Define 2015, extemporaneous thesaurus, Smart Define, viewed 28 September, 2026, <https://smartdefine.org/extemporaneous/thesaurus/synonyms>.
MLASmart Define. "extemporaneous thesaurus" 13 April 2015. Web. 28 September 2026. <https://smartdefine.org/extemporaneous/thesaurus/synonyms>