189 entries under severe topic. ×

1
dogmatic(adjective, exact)
1
dry
1
dyed-in-the-wool(adjective, set, strong, hard, tough)
1
fatiguing(adjective, hard, tough, rough)
1
forbidding(adjective, strong, hard, tough)
1
frosty
1
frowning(adjective, strong, hard, tough)
1
fundamental
1
grievous(adjective, hard, tough, harsh)
1
grueling(adjective, hard, tough, difficult)
1
hard-boiled(adjective, strong, hard, tough)
1
hard-line(adjective, strong, hard, tough)
1
hardheaded(adjective, strong, hard, tough)
1
imperial
1
irksome(adjective, tough, rough, difficult)
1
iron-fisted(adjective, tough, firm, harsh)
1
lean
1
mortified(adjective, strong, hard, tough)
1
mulish(adjective, strong, hard, tough)
1
murder(adjective, hard, tough, rough)
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APASmart Define. (2016). rigorous thesaurus. Retrieved September 23, 2026, from https://smartdefine.org/rigorous/thesaurus/synonyms
ChicagoSmart Define. 2016. "rigorous thesaurus" https://smartdefine.org/rigorous/thesaurus/synonyms (accessed September 23, 2026).
HarvardSmart Define 2016, rigorous thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/rigorous/thesaurus/synonyms>.
MLASmart Define. "rigorous thesaurus" 26 February 2016. Web. 23 September 2026. <https://smartdefine.org/rigorous/thesaurus/synonyms>