- Definitions|2
- Thesaurus|1.2k
- Abbreviations|0
| unquestionable(adjective, certain, dependable, undisputable, unerring) | |
| useful(adjective, dependable, unerring) | |
| assured(certain, unquestionable, undisputable, inevitable) | |
| constant(certain, reliable, trustworthy, unquestionable, undisputable) | |
| definite(adjective, clear, certain, valid, unquestionable) | |
| direct | |
| doubtless(adverb, certain, unquestionable, undisputable) | |
| errorless(perfect, precise, flawless, faultless, exquisite) | |
| faithful | |
| firm(noun, clear, certain, valid, unquestionable) | |
| guaranteed(adjective, clear, certain, flawless, valid) | |
| ideal | |
| incontestable(adjective, certain, unquestionable, undisputable) | |
| inevitable(adjective, certain, unquestionable, undisputable) | |
| omniscient(adjective, dependable, unerring) | |
| oracular | |
| precise(perfect, flawless, faultless, exquisite) | |
| right(adjective, precise, accurate) | |
| stable | |
| staunch |
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| APA | Smart Define. (2015). infallible thesaurus. Retrieved September 24, 2026, from https://smartdefine.org/infallible/thesaurus/synonyms |
| Chicago | Smart Define. 2015. "infallible thesaurus" https://smartdefine.org/infallible/thesaurus/synonyms (accessed September 24, 2026). |
| Harvard | Smart Define 2015, infallible thesaurus, Smart Define, viewed 24 September, 2026, <https://smartdefine.org/infallible/thesaurus/synonyms>. |
| MLA | Smart Define. "infallible thesaurus" 10 April 2015. Web. 24 September 2026. <https://smartdefine.org/infallible/thesaurus/synonyms> |