260 entries under adjective topic. ×

8
determined(strong, hard, tough, firm)
8
strong(hard, tough, firm, determined)
7
indomitable(characteristic, strong, hard, tough)
7
robust(strong, hard, tough, inflexible)
7
uncompliant(tough, resist, unreasonable, grim)
6
ferrous(strong, hard, tough, inflexible)
6
incompliant(resist, determined, resolute, persistent)
6
steely(dull, strong, hard, tough)
6
sturdy
6
tenacious(strong, tough, firm, solid)
5
brassbound(resist, determined, resolute, persistent)
5
cast-iron
5
die-hard(resist, determined, resolute, persistent)
5
harsh(characteristic, mean, hard, tough)
5
immovable(mean, strong, hard, tough)
5
remorseless(resist, determined, resolute, persistent)
5
resolute(hard, determined, resolution, rigid)
5
steadfast(strong, tough, firm, determined)
5
unbendable(resist, determined, resolute, persistent)
4
able-bodied
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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>