260 entries under adjective topic. ×

20
inexorable(characteristic, mean, strong, hard)
19
unyielding(characteristic, mean, strong, hard)
16
firm(noun, mean, strong, hard)
16
rigid(mean, strong, hard, tough)
15
adamant(mean, strong, hard, strength)
15
stubborn(characteristic, quality, mean, strong)
14
obdurate(strong, hard, tough, firm)
14
steel(strong, hard, strength, tough)
13
inflexible(mean, strong, hard, tough)
13
hard(noun, characteristic, mean, strong)
13
relentless(mean, strong, hard, tough)
13
unrelenting(mean, hard, tough, resist)
12
unbending(mean, strong, hard, tough)
11
gray(dull, silver, leaden, steely)
11
implacable(mean, strong, hard, tough)
11
uncompromising(mean, hard, resist, determined)
10
adamantine(set, strong, hard, tough)
10
intransigent(tough, resist, determined, resolute)
9
grim(tough, firm, resist, determined)
9
stern(characteristic, persistent, obstinate, insistent)
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APASmart Define. (2015). iron thesaurus. Retrieved September 25, 2026, from https://smartdefine.org/iron/thesaurus/synonyms
ChicagoSmart Define. 2015. "iron thesaurus" https://smartdefine.org/iron/thesaurus/synonyms (accessed September 25, 2026).
HarvardSmart Define 2015, iron thesaurus, Smart Define, viewed 25 September, 2026, <https://smartdefine.org/iron/thesaurus/synonyms>.
MLASmart Define. "iron thesaurus" 14 April 2015. Web. 25 September 2026. <https://smartdefine.org/iron/thesaurus/synonyms>