absolute, actual, admitting no question, apodictic, attestable, authenticatable, checkable, confirmable, demonstrable, demonstratable, evincible, factual, historical, inappealable, incontestable, incontrovertible, indisputable, indubitable, irrefragable, irrefutable, provable, real, self-evident, substantiatable, supportable, sustainable, testable, unanswerable, unconfutable, undeniable, unimpeachable, unquestionable, unrefutable, validatable