5
extemporary(adjective, free, casual, impulsive, spontaneous)
5
precipitate(noun, adjective, passionate, violent, thoughtless)
5
reflexive(adjective, impulsive, unwilling, obligatory, compulsory)
5
unguarded(adjective, thoughtless, impulse, unwary, nonpreparation)
5
unrehearsed(adjective, free, impulsive, spontaneous, unprepared)
4
ad-lib(adjective, spontaneous, unprepared, impromptu, unplanned)
4
candid
4
incidental(adjective, careless, chance, casual, random)
4
makeshift(adjective, free, informal, casual, snap)
4
thoughtless(adjective, careless, impetuous, inconsiderate, hasty)
4
uncontrived
4
unforeseen(adjective, chance, intention, unplanned, accidental)
3
coincidental
3
extemporized(adjective, spontaneous, unprepared, unplanned, unrehearsed)
3
headlong(noun, adjective, passionate, violent, thoughtless)
3
heedless(adjective, careless, thoughtless, inconsiderate)
3
hit-or-miss(adjective, careless, chance, casual, spontaneous)
3
hurried(adjective, impulsive, rash, unthinking)
3
ill-considered(adjective, impulsive)
3
indeliberate
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APASmart Define. (2015). unpremeditated thesaurus. Retrieved September 28, 2026, from https://smartdefine.org/unpremeditated/thesaurus/synonyms
ChicagoSmart Define. 2015. "unpremeditated thesaurus" https://smartdefine.org/unpremeditated/thesaurus/synonyms (accessed September 28, 2026).
HarvardSmart Define 2015, unpremeditated thesaurus, Smart Define, viewed 28 September, 2026, <https://smartdefine.org/unpremeditated/thesaurus/synonyms>.
MLASmart Define. "unpremeditated thesaurus" 10 April 2015. Web. 28 September 2026. <https://smartdefine.org/unpremeditated/thesaurus/synonyms>