- fanatic
- c.1525, "insane person," from L. fanaticus "mad, enthusiastic, inspired by a god," originally, "pertaining to a temple," from fanum "temple," related to festus "festive" (see feast). Current sense of "extremely zealous," especially in religion, is first attested 1647. The noun is from 1650, originally in religious sense, of Nonconformists.
"A fanatic is someone who can't change his mind and won't change the subject." [Winston Churchill]