Synonyms|131Antonyms|64|Broader|0Narrower|0Related|90
1
hardened
1
hardy
1
immovable
1
immutable
1
implacable
1
inelastic
1
inexorable
1
intransigent
1
inured
1
irreconcilable
1
relentless
1
rugged
1
steely
1
stern
1
stiff
1
stout
1
sturdy
1
tough
1
toughened
1
unaffected
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APASmart Define. (2015). cast-iron thesaurus. Retrieved September 27, 2026, from https://smartdefine.org/cast-iron/thesaurus/synonyms
ChicagoSmart Define. 2015. "cast-iron thesaurus" https://smartdefine.org/cast-iron/thesaurus/synonyms (accessed September 27, 2026).
HarvardSmart Define 2015, cast-iron thesaurus, Smart Define, viewed 27 September, 2026, <https://smartdefine.org/cast-iron/thesaurus/synonyms>.
MLASmart Define. "cast-iron thesaurus" 14 April 2015. Web. 27 September 2026. <https://smartdefine.org/cast-iron/thesaurus/synonyms>