Synonyms for fanatic

Noun

1. fanatic, fiend, enthusiast, partisan, partizan

usage: a person motivated by irrational enthusiasm (as for a cause); "A fanatic is one who can't change his mind and won't change the subject"--Winston Churchill

Adjective

1. fanatic, fanatical, overzealous, rabid, passionate (vs. passionless)

usage: marked by excessive enthusiasm for and intense devotion to a cause or idea; "rabid isolationist"