1
firm
1
frigid
1
frosted
1
frosty
1
frozen
1
grave
1
hard(adjective, careless, indifferent, cruel, apathetic)
1
hard-bitten(adjective, hard, careless, indifferent, cruel)
1
hard-boiled(noun, adjective, hard, careless, indifferent)
1
hard as nails(expression, adjective, idiom, hard, indifferent)
1
hardened to(expression, safe, unaffected, protected, resistant)
1
hardhearted(adjective, hard, careless, indifferent, cruel)
1
icy
1
immovable
1
immune to(expression, adjective, dead, insensitive, insusceptible)
1
immunised
1
immunized
1
immutable
1
impenitent(adjective, hard, careless, indifferent, cruel)
1
imperceptible(adjective, cold, indifferent, unresponsive, numb)
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APASmart Define. (2015). unsusceptible thesaurus. Retrieved September 29, 2026, from https://smartdefine.org/unsusceptible/thesaurus/synonyms
ChicagoSmart Define. 2015. "unsusceptible thesaurus" https://smartdefine.org/unsusceptible/thesaurus/synonyms (accessed September 29, 2026).
HarvardSmart Define 2015, unsusceptible thesaurus, Smart Define, viewed 29 September, 2026, <https://smartdefine.org/unsusceptible/thesaurus/synonyms>.
MLASmart Define. "unsusceptible thesaurus" 14 April 2015. Web. 29 September 2026. <https://smartdefine.org/unsusceptible/thesaurus/synonyms>