/ Dictionary / Index H heresiarch: Meaning and Definition of Find definitions for: he•re•si•arch Pronunciation: (hu-rē'zē-ärk", -sē-, her'u-sē-), [key] — n. a leader in heresy; the leader of a heretical sect. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. heres heresimach Related Content Daily Word Quiz: pugilist Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language