119 entries under severe topic. ×

1
fatiguing(adjective, tough, rough, difficult)
1
flinty(adjective, close, strong, hard, tough)
1
hang-tough(adjective, strong, hard, tough)
1
hard-boiled(adjective, calm, strong, hard, tough)
1
hard-core(adjective, strong, hard, tough)
1
hard-line(adjective, strong, hard, tough)
1
hard-shell(adjective, strong, hard, tough)
1
hardheaded(adjective, strong, hard, tough)
1
inflexible(adjective, strong, hard, tough)
1
irksome(adjective, tough, rough, difficult)
1
labored(adjective, hard, tough, rough)
1
merciless(adjective, tough, rough, difficult)
1
mortified(adjective, strong, hard, tough)
1
mulish(adjective, strong, hard, tough)
1
obdurate(adjective, close, strong, hard, tough)
1
stiff-necked(adjective, strong, hard, tough)
1
tiring(adjective, tough, rough, difficult)
1
troublesome(adjective, hard, tough, rough)
1
unfortunate(adjective, intense, unhappy, gloomy)
1
unrelenting(adjective, close, strong, hard, tough)
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APASmart Define. (2016). serious thesaurus. Retrieved September 26, 2026, from https://smartdefine.org/serious/thesaurus/synonyms
ChicagoSmart Define. 2016. "serious thesaurus" https://smartdefine.org/serious/thesaurus/synonyms (accessed September 26, 2026).
HarvardSmart Define 2016, serious thesaurus, Smart Define, viewed 26 September, 2026, <https://smartdefine.org/serious/thesaurus/synonyms>.
MLASmart Define. "serious thesaurus" 24 February 2016. Web. 26 September 2026. <https://smartdefine.org/serious/thesaurus/synonyms>