Webster’s Revised Unabridged Dictionary · 1913
Heresiarch
Her′e·si·arch, n. [L. haeresiarcha, Gr. αἱρεσιάρχης; αἵρεσις heresy + ἀρχός leader, ἄρχειν to lead: cf. F. hérésiarque.] A leader in heresy; the chief of a sect of heretics. Bp. Stillingfleet.