Webster's Revised Unabridged Dictionary · 1913

Heretic

Heretic , noun

[Latin haereticus, Greek {not transcribed} able to choose, heretical, from {not transcribed} to take, choose: compare French hérétique. See Heresy.]

1.
One who holds to a heresy; one who believes some doctrine contrary to the established faith or prevailing religion.
A man that is an heretic, after the first and second admonition, reject. — Titus iii. 10
2.
(Roman Catholic Church) One who having made a profession of Christian belief, deliberately and pertinaciously refuses to believe one or more of the articles of faith “determined by the authority of the universal church.” — Addis & Arnold