unanswerableEnglishOxford American Thesaurusunanswerable adjective 1 an unanswerable case for investment: irrefutable, inarguable, unarguable, indisputable, undeniable, incontestable, incontrovertible; conclusive, absolute, positive; rare irrefragable. ▷antonyms weak, flawed. 2 it was no use pondering on unanswerable questions: insoluble, unsolvable, insolvable, unresolvable, unexplainable, inexplicable, unascertainable. ▷antonyms obvious.