hoist by one's own petard

Cultural

To be caught in one's own trap: “The swindler cheated himself out of most of his money, and his victims were satisfied to see him hoist by his own petard.” A “petard” was an explosive device used in medieval warfare. To be hoisted, or lifted, by a petard literally means to be blown up.

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023