11
spontaneous(adjective, impulsive, willing)
10
unplanned(adjective, planned)
7
accidental(adjective, deliberate, unexpectedly)
6
offhand(adjective, careless, careful, abrupt, extemporaneous)
4
extemporaneous(adjective, improvised, rehearsed)
4
eye-opening
3
happy
2
ad-lib(adjective, adverb, manner, rehearsed)
2
impromptu(adjective, adverb, deliberate, unrehearsed, improvised)
2
inadvertent(adjective, accidental)
1
casual(adjective, deliberate, chance, random)
1
chance(adjective, accidental, unforeseeable)
1
extemporary
1
fortuitous(adjective, lucky, accidental)
1
improvised
1
haphazard(adjective, organization, plan)
1
rash(adjective, reasonable, sensible, careless, impulsive)
1
spur-of-the-moment
0
impulsive(adjective, cautious)
0
involuntary
10 years ago|2.1k views|share |citing 
APASmart Define. (2016). planned thesaurus. Retrieved September 21, 2026, from https://smartdefine.org/planned/thesaurus/antonyms
ChicagoSmart Define. 2016. "planned thesaurus" https://smartdefine.org/planned/thesaurus/antonyms (accessed September 21, 2026).
HarvardSmart Define 2016, planned thesaurus, Smart Define, viewed 21 September, 2026, <https://smartdefine.org/planned/thesaurus/antonyms>.
MLASmart Define. "planned thesaurus" 26 February 2016. Web. 21 September 2026. <https://smartdefine.org/planned/thesaurus/antonyms>