35 entries under hard topic. ×

22
unbearable(adjective, difficult, pain, complex)
22
complicated(adjective, difficulty, difficult, complex)
22
complex(adjective, difficult, number)
22
knotty(adjective, difficulty, difficult, complex)
21
problematic(adjective, difficult, complex)
21
stubborn(adjective, difficulty, difficult, complex)
21
thorny(adjective, difficulty, difficult, complex)
20
trying(adjective, difficulty, difficult, complex)
20
difficult(adjective, support, attitude, unpleasant)
20
ambitious(adjective, difficult, perfect, complex)
19
disturbing(adjective, difficult, complex)
19
far out(adjective, difficult, complex)
19
intricate(adjective, difficulty, difficult, complex)
19
knotted(adjective, difficulty, difficult, complex)
19
rugged(adjective, difficulty, difficult, complex)
18
labyrinthine(adjective, difficulty, difficult, complex)
18
oppressive(adjective, difficult, complex)
18
painful(adjective, difficult, complex)
18
sensitive(adjective, difficult, complex)
18
sticky(adjective, difficult, complex)
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APASmart Define. (2016). impossible thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/impossible/thesaurus/synonyms
ChicagoSmart Define. 2016. "impossible thesaurus" https://smartdefine.org/impossible/thesaurus/synonyms (accessed September 22, 2026).
HarvardSmart Define 2016, impossible thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/impossible/thesaurus/synonyms>.
MLASmart Define. "impossible thesaurus" 9 March 2016. Web. 22 September 2026. <https://smartdefine.org/impossible/thesaurus/synonyms>