19
certain(adjective, valid, undoubtable)
16
sure(adjective, clear, honest, certain, definite)
12
confident
11
clear(adjective, honest)
8
definite(adjective, clear, honest)
8
unambiguous
8
reliable(adjective, clear, honest)
7
determined(verb, adjective, clear, honest)
7
unquestionable(adjective, clear, honest)
6
positive(adjective, clear, honest)
6
self-confident
5
assured(verb, humble)
4
doubtless(adjective, adverb, clear, honest, likely)
4
probable(adjective, clear, honest)
4
trustworthy
4
undoubted(adjective, clear, honest)
4
well-documented
3
believable(adjective, clear, honest)
3
decisive
3
indisputable
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APASmart Define. (2016). dubious thesaurus. Retrieved September 23, 2026, from https://smartdefine.org/dubious/thesaurus/antonyms
ChicagoSmart Define. 2016. "dubious thesaurus" https://smartdefine.org/dubious/thesaurus/antonyms (accessed September 23, 2026).
HarvardSmart Define 2016, dubious thesaurus, Smart Define, viewed 23 September, 2026, <https://smartdefine.org/dubious/thesaurus/antonyms>.
MLASmart Define. "dubious thesaurus" 4 March 2016. Web. 23 September 2026. <https://smartdefine.org/dubious/thesaurus/antonyms>