52 entries under firm topic. ×

19
unyielding(adjective, characteristic, mean, strong, hard)
16
rigid(adjective, mean, strong, hard, tough)
15
adamant(adjective, mean, strong, hard, strength)
15
stubborn(adjective, characteristic, quality, mean, strong)
14
obdurate(adjective, strong, hard, tough)
13
inflexible(adjective, mean, strong, hard, tough)
13
hard(noun, adjective, characteristic, mean, strong)
13
relentless(adjective, mean, strong, hard, tough)
10
adamantine(adjective, set, strong, hard, tough)
9
grim(adjective, tough, resist, determined)
8
determined(adjective, strong, hard, tough)
8
strong(adjective, hard, tough, determined)
6
tenacious(adjective, strong, tough, solid)
5
steadfast(adjective, strong, tough, determined)
4
obstinate(adjective, set, mean, strong, hard)
4
set(verb, adjective, strong, tough)
4
stiff(adjective, resolute, rigid, inflexible)
3
dense(adjective, set, strong, hard, tough)
3
fast(adjective, strong, tough, solid)
3
indurate(adjective, set, mean, hard)
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APASmart Define. (2015). iron thesaurus. Retrieved September 26, 2026, from https://smartdefine.org/iron/thesaurus/synonyms
ChicagoSmart Define. 2015. "iron thesaurus" https://smartdefine.org/iron/thesaurus/synonyms (accessed September 26, 2026).
HarvardSmart Define 2015, iron thesaurus, Smart Define, viewed 26 September, 2026, <https://smartdefine.org/iron/thesaurus/synonyms>.
MLASmart Define. "iron thesaurus" 14 April 2015. Web. 26 September 2026. <https://smartdefine.org/iron/thesaurus/synonyms>