191 entries under tough topic. ×

4
indomitable(adjective, strong, hard, resolute)
4
recalcitrant(adjective, firm, persistent, obstinate)
4
rugged(adjective, strong, hard, severe)
4
square(adjective, moderate, severe, firm)
4
thick(adjective, strong, hard, firm)
4
unsparing(adjective, strong, hard, severe)
4
uptight(adjective, moderate, severe, firm)
3
condensed(adjective, hard, solid, inflexible)
3
hard-shell(adjective, strong, hard, severe)
3
impenetrable(adjective, set, strong, hard)
3
opinionated(adjective, firm, unreasonable, inflexible)
3
self-willed(adjective, firm, inflexible, obstinate)
3
serious(adjective, strong, hard, severe)
3
straight(adjective, correct, moderate, severe)
2
bitter(adjective, set, strong, hard)
2
burdensome(adjective, correct, severe, harsh)
2
cantankerous(firm, persistent, obstinate, stubborn)
2
concentrated(adjective, set, strong, hard, complete)
2
concrete(adjective, hard, correct, solid)
2
hard-boiled(adjective, mean, strong, hard)
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APASmart Define. (2015). rigid thesaurus. Retrieved September 28, 2026, from https://smartdefine.org/rigid/thesaurus/synonyms
ChicagoSmart Define. 2015. "rigid thesaurus" https://smartdefine.org/rigid/thesaurus/synonyms (accessed September 28, 2026).
HarvardSmart Define 2015, rigid thesaurus, Smart Define, viewed 28 September, 2026, <https://smartdefine.org/rigid/thesaurus/synonyms>.
MLASmart Define. "rigid thesaurus" 3 August 2015. Web. 28 September 2026. <https://smartdefine.org/rigid/thesaurus/synonyms>