apostate
1. [ adjective ] (religion) not faithful to religion or party or cause
Related terms: unfaithful
2. [ noun ] a disloyal person who forsakes his cause or religion or political party or friend etc.
Synonyms: renegade recreant ratter turncoat deserter
Related terms: quitter abandon denounce rat apostatize
Similar spelling:   apostatize
  apostatise
  Apostle
  apostasy
  apposite
  apostrophe
  apostleship