Of, relating to, or contemporary with the 12 Apostles.
Of, relating to, or derived from the teaching or practice of the 12 Apostles.
Of or relating to a succession of spiritual authority from the 12 Apostles, regarded by Anglicans, Roman Catholics, Eastern Orthodox, and some others to have been perpetuated by successive ordinations of bishops and to be requisite for valid orders and administration of sacraments.
Roman Catholic Church Of or relating to the pope as the successor of Saint Peter; papal.
Of or relating to a succession of spiritual authority from the 12 Apostles, regarded by Anglicans, Roman Catholics, Eastern Orthodox, and some others to have been perpetuated by successive ordinations of bishops and to be requisite for valid orders and administration of sacraments.
Roman Catholic Church Of or relating to the pope as the successor of Saint Peter; papal.
ap'os·tol'i·cal·ly adv., ap'os·tol·ic'i·ty (-stə-lĭs'ĭ-tē) n.
[ap-uh-stol-ik] 
əˈstɒl