n. A person deputed or authorized to perform the functions of another; a substitute in office: as, the Pope claims to be vicar of Jesus Christ on earth.n. In English ecclesiastical law, the priest of a parish the tithes of which belong to a chapter or religious house, or to a layman, and who receives only the smaller tithes or a salary.n. In the Roman Catholic Church, an ecclesiastic assisting a bishop and exercising jurisdiction in his name.