THESAURUS
unmistaken
actual, ascertained, attested, authenticated, categorically true, certain, certified, confirmed, corroborated, demonstrated, determined, documentary, effectual, established, factual, historical, not in error, objectively true, proved, real, substantiated, sure-enough, true, true as gospel, truthful, unconfuted, undenied, undoubted, unerroneous, unfallacious, unfalse, unquestionable, unrefuted, validated, veracious, verified, veritable