Crusade in Turkish

Any of a series of religious campaigns by Christian forces from the 11th to the 13th century, mostly to capture the Holy Land from the Muslims who occupied it.

(historical) Any of the Papally-endorsed military expeditions undertaken by the Christians of Latin Europe in the 11th to 13th centuries to reconquer the Levant from the Muslims, as well as expeditions along the Baltic Sea and against the Cathars.

(figuratively, sometimes, ironically) A grand, concerted effort towards some purportedly worthy cause.

(intransitive) To make a grand concerted effort toward some purportedly worthy cause.