1. a person who is very interested in a particular activity or subject: "a sports car enthusiast"
2. a person of intense and visionary Christian views.archaic, derogatory
Word Originmid 16th century (referring to a person believing that he or she is divinely inspired): via late Latin enthusiasta ‘kind of heretic’ from Greek enthousiastēs ‘person inspired by a god’, from enthousiazein (see enthusiasm).