126 entries under difficult topic. ×

20
esoteric(adjective, hard)
20
inextricable(adjective, hard, complicated, complexity)
20
painful(adjective, hard)
20
tight(adjective, hard)
19
anfractuous(adjective, hard)
19
grinding(adjective, hard)
19
nasty(adjective, hard)
19
operose(adjective, hard)
19
tangly(adjective, hard)
19
weighty(adjective, hard)
18
impossible(adjective, hard, number)
18
precarious(adjective, hard)
17
troubled(adjective, upset, hard, anxious)
15
convoluted(adjective, hard, simple, fancy)
14
puzzling(adjective, hard, fancy, heavy)
12
perplexing(adjective, hard, fancy, delicate)
11
obscure(adjective, hard, delicate, heavy)
10
abstruse(noun, adjective, hard, fancy)
10
mixed(adjective, fancy, involved, unity)
10
tortuous(adjective, sophisticated, involved, dense)
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APASmart Define. (2016). complex thesaurus. Retrieved September 20, 2026, from https://smartdefine.org/complex/thesaurus/synonyms
ChicagoSmart Define. 2016. "complex thesaurus" https://smartdefine.org/complex/thesaurus/synonyms (accessed September 20, 2026).
HarvardSmart Define 2016, complex thesaurus, Smart Define, viewed 20 September, 2026, <https://smartdefine.org/complex/thesaurus/synonyms>.
MLASmart Define. "complex thesaurus" 11 January 2016. Web. 20 September 2026. <https://smartdefine.org/complex/thesaurus/synonyms>