(1):
(a.) Pertaining to, or characterized by, apostasy; faithless to moral allegiance; renegade.
(2):
(v. i.) To apostatize.
(3):
(n.) One who has forsaken the faith, principles, or party, to which he before adhered; esp., one who has forsaken his religion for another; a pervert; a renegade.
(4):
(n.) One who, after having received sacred orders, renounces his clerical profession.