338 entries under strong topic. ×

7
mulish(adjective, mean, hard, tough)
7
rigorous(adjective, hard, complete, tough)
7
unflagging(adjective, tough, fit, solid)
7
vigorous(adjective, tough, fit, solid)
6
bold(adjective, vigorous, noble, resolute)
6
forceful(adjective, clear, sound, heavy)
6
grim(adjective, hard, tough, severe)
6
gritty(steady, resolution, bold, resolute)
6
harsh(adjective, mean, hard, tough)
6
impervious(adjective, set, hard, tough)
6
powerful(adjective, sound, tough, fit)
6
trusty(adjective, good, close, correct)
6
unbreakable(adjective, hard, tough, severe)
5
absolute(adjective, clear, complete, easy)
5
balanced(adjective, calm, secure, easy)
5
committed(adjective, determined, steady, fixed)
5
courageous(adjective, determined, vigorous, noble)
5
dauntless(adjective, vigorous, noble, bold)
5
hardened(adjective, set, hard, tough)
5
petrified(adjective, calm, set, hard)
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APASmart Define. (2016). firm thesaurus. Retrieved September 26, 2026, from https://smartdefine.org/firm/thesaurus/synonyms
ChicagoSmart Define. 2016. "firm thesaurus" https://smartdefine.org/firm/thesaurus/synonyms (accessed September 26, 2026).
HarvardSmart Define 2016, firm thesaurus, Smart Define, viewed 26 September, 2026, <https://smartdefine.org/firm/thesaurus/synonyms>.
MLASmart Define. "firm thesaurus" 31 March 2016. Web. 26 September 2026. <https://smartdefine.org/firm/thesaurus/synonyms>