Synonyms|1kAntonyms|253|Broader|5Narrower|1Related|546
5
immovable(adjective, set, strong, hard, tough)
5
methodical(noun, adjective, correct, solid, perfect)
5
puritanical(adjective, tough, severe, firm, harsh)
5
raw(adjective, severe)
5
unchangeable(adjective, hard, resolute, rigid, inflexible)
5
undeviating(adjective, severe, harsh, solid, exact)
5
unsparing(adjective, strong, hard, tough, severe)
4
acrimonious(adjective, tough, severe, harsh, grim)
4
acute(adjective, severe)
4
adamantine(adjective, set, strong, hard, tough)
4
ascetic
4
bleak(adjective, tough, severe, harsh, cruel)
4
brisk(adjective, severe, stringent, drastic)
4
challenging(adjective, difficult, awkward, thorough, demanding)
4
constant
4
crisp(adjective, severe)
4
detail-oriented
4
detail oriented(adjective, exact, strict, scrupulous, detailed)
4
determined(adjective, severe, harsh, solid, intense)
4
diligent(adjective, fastidious)
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HarvardSmart Define 2016, rigorous thesaurus, Smart Define, viewed 21 September, 2026, <https://smartdefine.org/rigorous/thesaurus/synonyms>.
MLASmart Define. "rigorous thesaurus" 26 February 2016. Web. 21 September 2026. <https://smartdefine.org/rigorous/thesaurus/synonyms>