heretic

 
Pronunciation: /ˈhɛrɪtɪk/

noun

  • a person believing in or practising religious heresy.
  • a person holding an opinion at odds with what is generally accepted.

Origin:

Middle English: from Old French heretique, via ecclesiastical Latin from Greek hairetikos 'able to choose' (in ecclesiastical Greek, 'heretical'), from haireomai 'choose'