307 entries under adjective topic. ×

1
feelingless(hard, indifferent, unfeeling, unkind)
1
firm(set, strong, hard, sound)
1
fixed(strong, sound, tough, solid)
1
formal(tough, firm, fixed, distant)
1
hard-as-nails(determined, serious, persistent, callous)
1
hard-boiled(hard, tough, harsh, indifferent)
1
hard-handed(set, strong, hard, continue)
1
hard-line(tough, firm, fixed, rigid)
1
hardboiled(tough, determined, serious, stiff)
1
hardened(set, strong, hard, tough)
1
hardhearted(hard, indifferent, unfeeling, unkind)
1
healthy(strong, hard, solid, heavy)
1
heartless(feeling, hard, cold, indifferent)
1
heavy(strong, hard, sound, tough)
1
heavy-duty(strong, sound, tough, solid)
1
hold the fort(expression, idiom, tough, firm)
1
hold the line(expression, idiom, tough, firm)
1
immovable(calm, strong, hard, cool)
1
impenetrable(set, strong, hard, firm)
1
imperceptive(hard, 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>