100 entries under hard topic. ×

1
imperceptive(adjective, indifferent, unkind, unresponsive)
1
incurious(adjective, indifferent, unkind, unresponsive)
1
indurated(adjective, set, strong, unfeeling)
1
inexorable(adjective, strong, tough, firm)
1
inflexible(adjective, set, strong, tough)
1
insensitive(adjective, tough, indifferent, cruel)
1
insusceptible(adjective, insensitive, unsusceptible)
1
obtuse(adjective, indifferent, unfeeling, unkind)
1
relentless(adjective, strong, tough, firm)
1
rigid(adjective, set, strong, tough)
1
seasoned(adjective, strong, solid, stiff)
1
sinewy(adjective, strong, sound, tough)
1
steeled(adjective, strong, solid, stiff)
1
stiff(adjective, set, strong, tough)
1
tactless(adjective, indifferent, unkind, unresponsive)
1
tenacious(adjective, strong, sound, tough)
1
thick-skinned(adjective, calm, cool, tough)
1
tough as nails(expression, adjective, idiom, strong)
1
unbending(adjective, strong, tough, fixed)
1
unconcerned(adjective, indifferent, unkind, unresponsive)
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APASmart Define. (2015). hard as nails thesaurus. Retrieved September 29, 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 29, 2026).
HarvardSmart Define 2015, hard as nails thesaurus, Smart Define, viewed 29 September, 2026, <https://smartdefine.org/hard_as_nails/thesaurus/synonyms>.
MLASmart Define. "hard as nails thesaurus" 10 April 2015. Web. 29 September 2026. <https://smartdefine.org/hard_as_nails/thesaurus/synonyms>