/
ˈhɛrɪsi/
n.
 (pl. heresies)
  - belief or opinion contrary to orthodox religious (especially Christian) doctrine.
 - opinion profoundly at odds with what is generally accepted.
 
Etymology
ME: from OFr. heresie, based on L. haeresis, from Gk hairesis ‘choice’ (in eccles. Gk ‘heretical sect’).