Wild and extravagant in opinions, particularly in religious opinions; excessively enthusiastic; possessed by a kind of frenzy. Hence we say, fanatic zeal; fanatic notions or opinions.

A person affected by excessive enthusiasm, particularly on religious subjects; one who indulges wild and extravagant notions of religion, and sometimes exhibits strange motions and postures, and vehement vociferation in religious worship. Fanatics sometimes affect to be inspired or to have intercourse with superior beings.