39
natural(adjective, calm, open, simple, plain)
27
involuntary(noun, adjective, reasonable, common, ordinary)
25
automatic(adjective, free, fake, natural, casual)
24
impulsive(noun, adjective, moving, simple, easy)
19
instinctive(noun, adjective, simple, easy, natural)
19
unpremeditated(noun, adjective, free, impulsive, planned)
17
unplanned(noun, adjective, free, fake, informal)
16
extemporaneous(noun, adjective, plain, impulsive, willing)
15
impromptu(adjective, adverb, free, plain, impulsive)
15
voluntary(adjective, feature, characteristic, free, deliberate)
14
innate(adjective, natural, instinctive, gut, automatic)
14
unprompted(adjective, plain, natural, thoughtless, impulsive)
14
instinctual(adjective, natural, unconscious, instinctive, automatic)
13
unforced(adjective, feature, characteristic, simple, regard)
12
unthinking(adjective, careless, natural, casual, emotional)
12
free(adjective, feature, characteristic, simple, fake)
11
offhand(noun, adjective, free, careless, casual)
11
inherent(adjective, reasonable, instinctive, automatic, intuitive)
11
mechanical(adjective, natural, routine, impulsive, instinctive)
11
gratuitous(adjective, feature, characteristic, free, deliberate)
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APASmart Define. (2015). spontaneous thesaurus. Retrieved February 21, 2019, from https://smartdefine.org/spontaneous/thesaurus/synonyms
ChicagoSmart Define. 2015. "spontaneous thesaurus" https://smartdefine.org/spontaneous/thesaurus/synonyms (accessed February 21, 2019).
HarvardSmart Define 2015, spontaneous thesaurus, Smart Define, viewed 21 February, 2019, <https://smartdefine.org/spontaneous/thesaurus/synonyms>.
MLASmart Define. "spontaneous thesaurus" 3 August 2015. Web. 21 February 2019. <https://smartdefine.org/spontaneous/thesaurus/synonyms>