77 entries under severe topic. ×

6
knotty(adjective, hard, rough, difficult)
6
operose(adjective, tough, difficulty, rough)
6
threatening(adjective, tough, unpleasant, important)
6
trying(adjective, tough, rough, difficult)
6
weighty(adjective, harsh, heavy, painful)
5
exacting(adjective, tough, rough, difficult)
5
harsh(adjective, hard, great, rough)
5
labored(adjective, tough, difficult, heavy)
5
stiff(adjective, great, tough, difficult)
5
troublesome(adjective, hard, tough, evil)
4
fell(adjective, tough, unpleasant, important)
4
hairy(adjective, bad, rough, difficult)
4
ugly(adjective, bad, hard, tough)
3
complicated(adjective, hard, tough, rough)
3
grave(adjective, tough, difficult, unpleasant)
3
mean(adjective, bad, rough, nasty)
3
murder(adjective, hard, tough, rough)
3
painful(adjective, hard, tough, difficult)
3
rigorous(adjective, hard, tough, rough)
3
taxing(adjective, hard, tough, rough)
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APASmart Define. (2015). formidable thesaurus. Retrieved September 21, 2026, from https://smartdefine.org/formidable/thesaurus/synonyms
ChicagoSmart Define. 2015. "formidable thesaurus" https://smartdefine.org/formidable/thesaurus/synonyms (accessed September 21, 2026).
HarvardSmart Define 2015, formidable thesaurus, Smart Define, viewed 21 September, 2026, <https://smartdefine.org/formidable/thesaurus/synonyms>.
MLASmart Define. "formidable thesaurus" 17 July 2015. Web. 21 September 2026. <https://smartdefine.org/formidable/thesaurus/synonyms>