183 entries under firm topic. ×

30
stern(adjective, hard, tough, easy, severe)
30
unbendable(adjective, resist, determined, unreasonable)
28
rigorous(adjective, strong, hard, tough, correct)
28
tight(adjective, close, strong, secure, severe)
27
refractory(adjective, hard, tough, strain)
25
resistant(adjective, strong, strain, stiff)
25
steady(adjective, feature, state, characteristic, complete)
22
adamantine(adjective, strong, hard, tough, severe)
22
durable(adjective, strong, strain, stiff)
22
tough(adjective, mean, strong, hard, easy)
21
fast(adjective, complete, secure, strain)
20
austere(adjective, strong, hard, tough, severe)
20
solid(adjective, strong, hard, complete, secure)
20
enduring(adjective, strain, fixed, stiff)
19
exacting(adjective, hard, tough, easy, severe)
18
stringent(adjective, hard, tough, severe, rough)
17
inelastic(adjective, hard, tough, severe)
16
set in stone(expression, adjective, idiom, mean, hard)
15
iron(adjective, mean, strong, hard, tough)
15
strait-laced(adjective, tough, correct, severe)
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APASmart Define. (2015). rigid thesaurus. Retrieved September 25, 2026, from https://smartdefine.org/rigid/thesaurus/synonyms
ChicagoSmart Define. 2015. "rigid thesaurus" https://smartdefine.org/rigid/thesaurus/synonyms (accessed September 25, 2026).
HarvardSmart Define 2015, rigid thesaurus, Smart Define, viewed 25 September, 2026, <https://smartdefine.org/rigid/thesaurus/synonyms>.
MLASmart Define. "rigid thesaurus" 3 August 2015. Web. 25 September 2026. <https://smartdefine.org/rigid/thesaurus/synonyms>