THESAURUS
turntail
apostate, backslider, bolter, collaborationist, collaborator, convert, defector, deserter, fifth columnist, mugwump, proselyte, quisling, recidivist, recreant, renegade, renegado, renegate, reversionist, runagate, schismatic, seceder, secessionist, separatist, strikebreaker, tergiversant, tergiversator, traitor, turnabout, turncoat