noun pl. heresies -·sies

1. 1. a religious belief opposed to the orthodox doctrines of a church; esp., such a belief specifically denounced by the church
   2. the rejection of a belief that is a part of church dogma
2. any opinion (in philosophy, politics, etc.) opposed to official or established views or doctrines
3. the holding of any such belief or opinion

Etymology: ME heresie < OFr < L haeresis, school of thought, sect, in LL(Ec), heresy < Gr hairesis, a taking, selection, school, sect, in LGr(Ec), heresy < hairein, to take