say it: fuh-NAT-ik
fanatic is a noun and adjective meaning "a person motivated by irrational enthusiasm (as for a cause)". It carries 2 recorded senses.
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”
marked by excessive enthusiasm for and intense devotion to a cause or idea
“rabid isolationist”
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for fanatic come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.