A title dating from the 6th cent. for the bishops of the five chief sees of Christendom: Rome, Alexandria, Antioch, Constantinople, and Jerusalem, whose jurisdiction extended over the adjoining territories. In more recent times the title has been given to the heads of certain other autocephalous Churches of the East (Russia, Serbia, Romania, Bulgaria, and Georgia). In the (Latin) RC Church it is used in an honorific way for the bishops of certain sees, e.g. Venice. See also Oecumenical Patriarch and Catholicos.