9
stable(adjective, clear, weak, sound, soft)
8
steady(adjective, clear, sound, stable, fixed)
8
peaceful
7
self-confident
7
strong(adjective, clear, sound, steady)
6
firm(noun, adjective, clear, sound, steady)
6
sturdy(adjective, solid, durable)
4
certain(adjective, clear, sound, steady)
4
constant(adjective, clear, sound, sympathetic, steady)
3
adaptive
2
sane(adjective, sound, reasonable, stupid, insane)
2
balanced
2
lasting
2
changeless
2
easy(adjective, clear, sound, steady)
2
fixed
2
level(rough, irregular, broken, indefinite)
2
loyal
2
net force
2
placid
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APASmart Define. (2016). unstable thesaurus. Retrieved September 23, 2026, from https://smartdefine.org/unstable/thesaurus/antonyms
ChicagoSmart Define. 2016. "unstable thesaurus" https://smartdefine.org/unstable/thesaurus/antonyms (accessed September 23, 2026).
HarvardSmart Define 2016, unstable thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/unstable/thesaurus/antonyms>.
MLASmart Define. "unstable thesaurus" 26 February 2016. Web. 23 September 2026. <https://smartdefine.org/unstable/thesaurus/antonyms>