191 entries under tough topic. ×

33
adamant(adjective, mean, strong, hard)
32
obstinate(adjective, mean, hard, moderate)
31
harsh(adjective, mean, strong, hard)
30
stern(adjective, hard, easy, severe)
28
rigorous(adjective, strong, hard, correct)
27
refractory(adjective, hard, strain, firm)
25
hard-nosed(adjective, mean, strong, hard)
22
adamantine(adjective, strong, hard, severe)
20
austere(adjective, strong, hard, severe)
20
solid(adjective, strong, hard, complete, secure)
19
exacting(adjective, hard, easy, severe)
19
robust(adjective, strong, hard, strain)
18
stringent(adjective, hard, severe, rough)
17
inelastic(adjective, hard, severe, firm)
16
set in stone(expression, adjective, idiom, mean, hard)
15
iron(adjective, mean, strong, hard)
15
strait-laced(adjective, correct, severe, firm)
14
demanding(adjective, hard, easy, severe)
14
formal(adjective, correct, severe, firm)
14
implacable(adjective, mean, strong, hard)
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APASmart Define. (2015). rigid thesaurus. Retrieved September 27, 2026, from https://smartdefine.org/rigid/thesaurus/synonyms
ChicagoSmart Define. 2015. "rigid thesaurus" https://smartdefine.org/rigid/thesaurus/synonyms (accessed September 27, 2026).
HarvardSmart Define 2015, rigid thesaurus, Smart Define, viewed 27 September, 2026, <https://smartdefine.org/rigid/thesaurus/synonyms>.
MLASmart Define. "rigid thesaurus" 3 August 2015. Web. 27 September 2026. <https://smartdefine.org/rigid/thesaurus/synonyms>