\En*thu"si*ast\, n. [Gr. ?: cf. F. enthousiaste.]
One moved or actuated by enthusiasm; as:
(a) One who imagines himself divinely inspired, or possessed
    of some special revelation; a religious madman; a
    fanatic.
(b) One whose mind is wholly possessed and heated by what
    engages it; one who is influenced by a peculiar; fervor
    of mind; an ardent and imaginative person.
          Enthusiasts soon understand each other. --W.
                                               Irving.
Syn: Visionary; fanatic; devotee; zealot.