Definition of crusade

• a series of actions advancing a principle or tending toward a particular end; "he supported populist campaigns"; "they worked in the cause of world peace"; "the team was ready for a drive toward the pennant"; "the movement to end slavery"; "contributed to the war effort"
• any of the more or less continuous military expeditions in the 11th to 13th centuries when Christian powers of Europe tried to recapture the Holy Land from the Muslims
• exert oneself continuously, vigorously, or obtrusively to gain an end or engage in a crusade for a certain cause or person; be an advocate for; "The liberal party pushed for reforms"; "She is crusading for womens rights"; "The Dean is pushing for his favorite candidate"