307 entries under adjective topic. ×

1
imperturbable(calm, cool, collected, unflappable)
1
in fine feather(expression, idiom, strong, sound)
1
incompliant(tough, firm, fixed, distant)
1
incurious(hard, indifferent, unkind, unresponsive)
1
indurated(set, strong, hard, unfeeling)
1
inelastic(tough, firm, fixed, distant)
1
inexorable(strong, hard, tough, firm)
1
inflexible(set, strong, hard, tough)
1
insensitive(hard, tough, indifferent, cruel)
1
insusceptible(hard, insensitive, unsusceptible)
1
intractable(tough, firm, fixed, distant)
1
locked in(expression, tough, firm, distant)
1
muscular(strong, sound, tough, solid)
1
nerveless(calm, cool, steady, tranquil)
1
nonchalant(calm, cool, steady, unaffected)
1
obtuse(hard, indifferent, unfeeling, unkind)
1
pitiless(cruel, vicious, fixed, unfeeling)
1
reinforced(strong, sound, tough, solid)
1
relentless(strong, hard, tough, firm)
1
reserved(tough, firm, fixed, distant)
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APASmart Define. (2015). hard as nails thesaurus. Retrieved September 28, 2026, from https://smartdefine.org/hard_as_nails/thesaurus/synonyms
ChicagoSmart Define. 2015. "hard as nails thesaurus" https://smartdefine.org/hard_as_nails/thesaurus/synonyms (accessed September 28, 2026).
HarvardSmart Define 2015, hard as nails thesaurus, Smart Define, viewed 28 September, 2026, <https://smartdefine.org/hard_as_nails/thesaurus/synonyms>.
MLASmart Define. "hard as nails thesaurus" 10 April 2015. Web. 28 September 2026. <https://smartdefine.org/hard_as_nails/thesaurus/synonyms>