Unquestionable means so clearly true or certain that no one could reasonably doubt it. When something is unquestionable, it's beyond dispute or debate.

If a student solves a math problem and shows all their work correctly, their answer is unquestionable. When a security camera captures someone stealing a bike, the evidence is unquestionable. The word describes facts, proof, or qualities that are so obvious or well-established that arguing against them would be pointless.

You might describe someone's unquestionable talent at the piano after hearing them play a difficult concerto flawlessly, or admire a friend's unquestionable loyalty after they've stood by you through tough times. A scientist's unquestionable integrity means their honesty is beyond doubt.

Something questionable raises doubts, while something unquestionable eliminates them. When a teacher has unquestionable authority in the classroom, students understand that certain rules aren't up for debate.

Be careful with this word, though. People sometimes claim things are unquestionable when they actually deserve examination. True unquestionable facts, like gravity pulling objects downward or water freezing at 32°F (0°C), stand up to any scrutiny. They don't need someone declaring them unquestionable because the evidence speaks for itself.