Mission meaning : A set of tasks that fulfills a purpose or duty; an assignment set by an employer, or by oneself. Religious evangelism. (in the plural, "the missions") third world charities, particularly those which preach as well as provide aid. (Catholic tradition) an infrequent gathering of religious believers in a parish, usually part of a larger regional event with a central theme. A number of people appointed to perform any service; a delegation; an embassy. Dismissal; discharge from service A settlement or building serving as a base for missionary work. To send on a mission. Do missionary work, proselytize