Synonyms|1kAntonyms|253|Broader|5Narrower|1Related|546

140 entries under hard topic. ×

12
difficult(adjective, severe, rough, harsh)
12
right(noun, adjective, complete, correct)
11
tough(adjective, strong, severe, rough)
10
obdurate(adjective, strong, tough, severe)
9
bitter(adjective, strong, tough, severe)
9
oppressive(adjective, tough, severe, rough)
8
arduous(adjective, tough, severe, rough)
8
inclement(adjective, tough, severe, rough)
8
relentless(adjective, strong, tough, severe)
8
rough(adjective, strong, tough, severe)
8
rugged(adjective, strong, tough, severe)
8
unbending(adjective, strong, tough, severe)
7
brutal(adjective, tough, severe, rough)
7
firm(noun, adjective, strong, complete)
7
grim(adjective, strong, tough, severe)
7
inexorable(adjective, strong, tough, severe)
7
laborious(adjective, tough, severe, rough)
7
obstinate(adjective, severe, resolute, rigid)
6
adamant(adjective, strong, tough, harsh)
6
astringent(adjective, strong, tough, severe)
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APASmart Define. (2016). rigorous thesaurus. Retrieved September 23, 2026, from https://smartdefine.org/rigorous/thesaurus/synonyms
ChicagoSmart Define. 2016. "rigorous thesaurus" https://smartdefine.org/rigorous/thesaurus/synonyms (accessed September 23, 2026).
HarvardSmart Define 2016, rigorous thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/rigorous/thesaurus/synonyms>.
MLASmart Define. "rigorous thesaurus" 26 February 2016. Web. 23 September 2026. <https://smartdefine.org/rigorous/thesaurus/synonyms>