73 entries under difficult topic. ×

7
opaque(adjective, hard, obscure, uncertain)
6
concealed(adjective, evil, obscure, dark)
6
knotty(adjective, hard, fancy, evil, obscure)
6
vague(adjective, obscure, uncertain, doubtful)
5
baffling(adjective, hard, obscure, dark)
5
impenetrable(adjective, obscure, strange, deep)
4
tricky(adjective, hard, complex, sophisticated)
3
thorny(adjective, hard, delicate, loose)
3
convoluted(adjective, hard, fancy, obscure)
3
equivocal(adjective, obscure, dark, strange)
3
unclear(adjective, hard, obscure, loose)
2
arduous(adjective, hard, fancy, complex)
2
challenging(adjective, obscure, inaccessible)
2
entangled(adjective, hard, fancy, obscure)
2
hard(adjective, fancy, obscure, heavy)
2
labyrinthine(adjective, hard, fancy, obscure)
2
muddy(adjective, obscure, uncertain, vague)
2
problematic(adjective, hard, fancy, complex)
2
tangled(adjective, hard, obscure, complex)
2
unintelligible(adjective, hard, obscure, delicate)
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APASmart Define. (2015). abstruse thesaurus. Retrieved September 22, 2026, from https://smartdefine.org/abstruse/thesaurus/synonyms
ChicagoSmart Define. 2015. "abstruse thesaurus" https://smartdefine.org/abstruse/thesaurus/synonyms (accessed September 22, 2026).
HarvardSmart Define 2015, abstruse thesaurus, Smart Define, viewed 22 September, 2026, <https://smartdefine.org/abstruse/thesaurus/synonyms>.
MLASmart Define. "abstruse thesaurus" 10 April 2015. Web. 22 September 2026. <https://smartdefine.org/abstruse/thesaurus/synonyms>