Unanswerable

(a.) Not answerable; irrefutable; conclusive; decisive; as, he have an unanswerable argument.

Thesaurus Entries

absolute, actual, admitting no question, chartered, confirmable, demonstrable, demonstratable, excepted, excused, exempt, exempted, factual, favored, historical, immune, inappealable, incontestable, incontrovertible, indisputable, indubitable, irrefragable, irrefutable, irresponsible, let off, licensed, permitted, privileged, provable, real, released, self-evident, spared, testable, unaccountable, unconfutable, undeniable, unimpeachable, unliable, unquestionable, unrefutable, unsubject, verifiable