255 entries under hard topic. ×

18
strenuous(adjective, dull, great, tough)
18
cruel(adjective, nasty, harsh, complex)
18
daedal(adjective, complex, involved, complicated)
18
toilful(adjective, complex, awkward, demanding)
18
unbearable(adjective, complex)
16
delicate(adjective, awkward, uneasy, tricky)
16
exacting(adjective, dull, tough, severe)
16
fussy(adjective, tough, harsh, particular)
14
formidable(adjective, tough, severe, evil)
14
heavy(adjective, dull, tough, severe)
13
abstruse(adjective, obscure, strange, uncertain)
13
exhausting(adjective, dull, tough, awkward)
13
perplexing(adjective, fancy, obscure, delicate)
12
obscure(adjective, strange, uncertain, complex)
11
critical(adjective, crabby, cranky, meticulous)
11
puzzling(adjective, fancy, obscure, strange)
11
rigorous(adjective, severe, rough, harsh)
11
unpleasant(adjective, severe, evil, rough)
11
uphill(adjective, great, tough, easy)
10
hairy(noun, adjective, severe, rough)
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ChicagoSmart Define. 2016. "difficult thesaurus" https://smartdefine.org/difficult/thesaurus/synonyms (accessed September 21, 2026).
HarvardSmart Define 2016, difficult thesaurus, Smart Define, viewed 21 September, 2026, <https://smartdefine.org/difficult/thesaurus/synonyms>.
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