2
powerful(adjective, strong, sound, tough, solid)
2
puissant(adjective, strong)
2
resistant(adjective, strong, hard, solid, stiff)
2
robust(adjective, strong, hard, sound, tough)
2
rocky(adjective, set, strong, hard, compact)
2
solid(adjective, set, strong, hard, sound)
2
steely(adjective, strong, hard, tough, stiff)
2
stony(adjective, set, strong, hard, indifferent)
2
stout(adjective, strong, hard, sound, tough)
2
strapping(adjective, strong, hard, sound, tough)
2
strong-willed(adjective, serious, resolute, persistent, driven)
2
sturdy(adjective, strong, hard, sound, tough)
2
vigorous(adjective, strong, hard, sound, tough)
1
able(adjective, strong, sound, tough, solid)
1
able-bodied(adjective, strong, sound, tough, solid)
1
active(adjective, strong, sound, tough, solid)
1
aloof(adjective, hard, tough, firm, indifferent)
1
assured(adjective, calm, cool, steady, tranquil)
1
athletic(adjective, strong, sound, tough, solid)
1
beefy
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APASmart Define. (2015). hard as nails thesaurus. Retrieved September 26, 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 26, 2026).
HarvardSmart Define 2015, hard as nails thesaurus, Smart Define, viewed 26 September, 2026, <https://smartdefine.org/hard_as_nails/thesaurus/synonyms>.
MLASmart Define. "hard as nails thesaurus" 10 April 2015. Web. 26 September 2026. <https://smartdefine.org/hard_as_nails/thesaurus/synonyms>