255 entries under hard topic. ×

9
baffling(adjective, obscure, strange, uncertain)
9
obstinate(adjective, tough, stubborn, complicated)
9
stiff(adjective, tough, severe, rough)
8
deep(adjective, severe, meaning, abstract)
8
mysterious(adjective, obscure, strange, complex)
8
recondite(adjective, fancy, obscure, strange)
8
uncertain(noun, adjective, severe, obscure)
7
effortful(adjective, great, tough, rough)
7
cantankerous(adjective, tough, evil, rough)
7
challenging(adjective, great, tough, obscure)
7
dangerous(noun, adjective, tough, severe)
7
harsh(adjective, tough, severe, rough)
7
problem(noun, adjective, tough, grim)
7
problematical(adjective, complex, awkward, demanding)
7
tiresome(adjective, tough, severe, heavy)
7
unyielding(adjective, tough, severe, wild)
7
wearisome(adjective, dull, tough, rough)
6
irritating(adjective, dull, tough, rough)
5
abstract(adjective, obscure, complex, complicated)
5
bothersome(adjective, tough, severe, rough)
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APASmart Define. (2016). difficult thesaurus. Retrieved September 21, 2026, from https://smartdefine.org/difficult/thesaurus/synonyms
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>.
MLASmart Define. "difficult thesaurus" 24 March 2016. Web. 21 September 2026. <https://smartdefine.org/difficult/thesaurus/synonyms>