17
proper(adjective, hard, correct, right, severe)
17
stiff(adjective, hard, severe, rough, difficult)
16
nice(noun, adjective, feature, correct, slight)
15
close(adjective, feature, correct, slight, harsh)
15
conscientious(adjective, thoughtful, sober, truth, honorable)
15
uncompromising(adjective, hard, severe, rough, difficult)
15
unyielding(adjective, strong, hard, tough, severe)
13
particular(noun, adjective, correct, fine, solid)
13
unerring(adjective, correct, solid, perfect, exact)
12
difficult(adjective, hard, severe, rough, harsh)
12
faithful(noun, adjective, correct, right, appropriate)
12
perfectionist
12
punctual(adjective, correct, solid, exact, proper)
12
right(noun, adjective, hard, complete, correct)
11
explicit(noun, adjective, correct, solid, perfect)
11
just(adjective, correct, right, appropriate, solid)
11
thorough(adjective, thoughtful, sober, cautious, prudent)
11
tough(adjective, strong, hard, severe, rough)
10
obdurate(adjective, strong, hard, tough, severe)
10
sharp(noun, adjective, correct, severe, harsh)
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APASmart Define. (2016). rigorous thesaurus. Retrieved September 21, 2026, from https://smartdefine.org/rigorous/thesaurus/synonyms
ChicagoSmart Define. 2016. "rigorous thesaurus" https://smartdefine.org/rigorous/thesaurus/synonyms (accessed September 21, 2026).
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>