( often initial capital letter ) 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.

any war carried on under papal sanction.

any vigorous, aggressive movement for the defense or advancement of an idea, cause, etc.

a crusade against child abuse.

to go on or engage in a crusade.

noun

cause , demonstration , drive , evangelism , expedition , holy war , jihad , march , movement , push , campaign , rally , war