Synonyms|131Antonyms|64|Broader|0Narrower|0Related|90
5
iron
3
firm
3
hard
3
inflexible(intent, hard-and-fast)
3
rigid
3
robust
3
solid
2
rigorous
2
strong
2
unbending(inflexible, intent, hard-and-fast)
2
unchangeable(inflexible, intent, hard-and-fast)
2
uncompromising
1
adamant
1
certain(definite, sure, inflexible, intent, hard-and-fast)
1
definite(adjective, certain, sure, inflexible, intent)
1
dour
1
durable
1
flinty
1
grim
1
hard-core
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APASmart Define. (2015). cast-iron thesaurus. Retrieved September 20, 2026, from https://smartdefine.org/cast-iron/thesaurus/synonyms
ChicagoSmart Define. 2015. "cast-iron thesaurus" https://smartdefine.org/cast-iron/thesaurus/synonyms (accessed September 20, 2026).
HarvardSmart Define 2015, cast-iron thesaurus, Smart Define, viewed 20 September, 2026, <https://smartdefine.org/cast-iron/thesaurus/synonyms>.
MLASmart Define. "cast-iron thesaurus" 14 April 2015. Web. 20 September 2026. <https://smartdefine.org/cast-iron/thesaurus/synonyms>