The word "unquestionable" implies something that is beyond doubt, undeniable, and indisputable. Its antonyms, on the other hand, signify doubt, ambiguity, or uncertainty. Some antonyms for unquestionable include disputable, debatable, uncertain, questionable, doubtful, and ambiguous. For instance, a claim or statement that lacks evidence, basis, or credibility may be regarded as disputable or questionable. Similarly, a situation that presents conflicting information or varying interpretations may be considered uncertain or ambiguous. The antonyms for unquestionable remind us that not everything is black and white, and we should always subject claims and assertions to scrutiny and critical thinking.