142 entries under firm topic. ×

6
constant(adjective, calm, strong, secure)
6
grim(adjective, strong, hard, severe)
6
hale(adjective, strong, sound, fit)
6
headstrong(adjective, hard, rough, difficult)
6
implacable(adjective, mean, strong, hard)
6
inured(noun, adjective, strong, hard, sound)
6
lusty(adjective, strong, fit, solid)
5
bullheaded(adjective, strong, hard, difficult)
5
dogged(adjective, mean, strong, hard)
5
reliable(adjective, calm, strong, secure)
5
rocklike(adjective, difficult, stiff, rigid)
5
thick(adjective, person, set, body, strong)
4
aloof(adjective, calm, mean, hard, cool)
4
hard as nails(expression, adjective, idiom, strong, hard)
4
intransigent(adjective, determined, resolute, obstinate)
4
mulish(adjective, mean, strong, hard)
4
persevering(adjective, determined, unreasonable, grim)
4
pertinacious(adjective, determined, resolute, obstinate)
4
refractory(adjective, hard, rough, grim)
4
set in stone(expression, adjective, idiom, calm, mean)
10 years ago|60k views|share |citing 
APASmart Define. (2016). tough thesaurus. Retrieved September 28, 2026, from https://smartdefine.org/tough/thesaurus/synonyms
ChicagoSmart Define. 2016. "tough thesaurus" https://smartdefine.org/tough/thesaurus/synonyms (accessed September 28, 2026).
HarvardSmart Define 2016, tough thesaurus, Smart Define, viewed 28 September, 2026, <https://smartdefine.org/tough/thesaurus/synonyms>.
MLASmart Define. "tough thesaurus" 30 March 2016. Web. 28 September 2026. <https://smartdefine.org/tough/thesaurus/synonyms>