<p><strong>Noun</strong></p><ul><li>Often Crusade.</li><li>any of the military expeditions undertaken by the Christians of Europe in the 11th, 12th, and 13th centuries for the recovery of the Holy Land from the Muslims.</li><li>any war carried on under papal sanction.</li><li>any vigorous, aggressive movement for the defense or advancement of an idea, cause, etc.: a crusade against child abuse.</li></ul><p><strong>Verb</strong></p><ul><li>(used without object) crusaded, crusading.</li><li>to go on or engage in a crusade.</li></ul>