Unconquerable means impossible to defeat or overcome. When something is unconquerable, it cannot be conquered, beaten, or brought under control, no matter how hard others try.

A castle built on a high cliff with thick walls and deep defenses might seem unconquerable to attacking armies. An athlete with an unconquerable spirit refuses to give up, even when losing or injured. Their determination cannot be broken. Some diseases were once considered unconquerable until scientists discovered cures through years of research.

The word often describes inner qualities like courage, hope, or will, as well as physical strength. A person facing a serious challenge might have an unconquerable attitude, meaning they won't let fear or difficulty defeat their resolve. When the poet William Ernest Henley wrote “I am the master of my fate, I am the captain of my soul,” he was expressing an unconquerable spirit despite his own physical suffering.

Mount Everest seemed unconquerable until 1953, when Edmund Hillary and Tenzing Norgay finally reached its summit. What seems unconquerable in one era might eventually be overcome through persistence, creativity, and courage, but the word captures that sense of a challenge so immense it appears impossible to defeat.