127 entries under tough topic. ×

5
distressing(adjective, severe, rough, difficult)
4
firm(adjective, strong, hard, severe)
4
relentless(adjective, close, strong, hard)
4
rigid(adjective, strong, hard, severe)
4
strong(adjective, hard, firm, solid)
3
dull(adjective, severe, dark, gloomy)
3
frowning(adjective, strong, hard, severe)
3
practical(adjective, calm, plain, dark)
3
unbending(adjective, close, strong, hard)
3
unyielding(adjective, strong, hard, severe)
2
bullheaded(adjective, strong, hard, severe)
2
deadpan(adjective, set, severe, honest)
2
forbidding(adjective, close, strong, hard)
2
harsh(adjective, strong, hard, severe)
2
impassive(adjective, calm, restrained, rational)
2
implacable(adjective, strong, hard, severe)
2
indomitable(adjective, strong, hard, resolute)
2
inexorable(adjective, close, strong, hard)
2
realistic(adjective, calm, sensible, dark)
2
rigorous(adjective, strong, hard, severe)
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APASmart Define. (2016). serious thesaurus. Retrieved September 29, 2026, from https://smartdefine.org/serious/thesaurus/synonyms
ChicagoSmart Define. 2016. "serious thesaurus" https://smartdefine.org/serious/thesaurus/synonyms (accessed September 29, 2026).
HarvardSmart Define 2016, serious thesaurus, Smart Define, viewed 29 September, 2026, <https://smartdefine.org/serious/thesaurus/synonyms>.
MLASmart Define. "serious thesaurus" 24 February 2016. Web. 29 September 2026. <https://smartdefine.org/serious/thesaurus/synonyms>