122 entries under hard topic. ×

4
rigid(adjective, strong, tough, severe)
4
strong(adjective, tough, firm, solid)
4
violent(adjective, severe, rough, difficult)
3
frowning(adjective, strong, tough, severe)
3
unbending(adjective, close, strong, tough)
3
unyielding(adjective, strong, tough, severe)
2
bullheaded(adjective, strong, tough, severe)
2
forbidding(adjective, close, strong, tough)
2
harsh(adjective, strong, tough, severe)
2
implacable(adjective, strong, tough, severe)
2
indomitable(adjective, strong, tough, resolute)
2
inexorable(adjective, close, strong, tough)
2
rigorous(adjective, strong, tough, severe)
2
steely(adjective, strong, tough, severe)
2
strict(adjective, strong, tough, severe)
1
onerous(adjective, tough, severe, rough)
1
astringent(adjective, close, strong, tough)
1
authoritarian(adjective, strong, tough, severe)
1
bitter(adjective, strong, tough, severe)
1
bothersome(adjective, tough, rough, difficult)
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APASmart Define. (2016). serious thesaurus. Retrieved September 27, 2026, from https://smartdefine.org/serious/thesaurus/synonyms
ChicagoSmart Define. 2016. "serious thesaurus" https://smartdefine.org/serious/thesaurus/synonyms (accessed September 27, 2026).
HarvardSmart Define 2016, serious thesaurus, Smart Define, viewed 27 September, 2026, <https://smartdefine.org/serious/thesaurus/synonyms>.
MLASmart Define. "serious thesaurus" 24 February 2016. Web. 27 September 2026. <https://smartdefine.org/serious/thesaurus/synonyms>