The Collaborative International Dictionary of English v.0.48:

Fanatism \Fan"a*tism\, n. [Cf. F. fanatisme. Cf. Fanaticism.]
   Fanaticism. [R.] --Gibbon.
   [1913 Webster]

WordNet (r) 3.0 (2006):

fanatism
    n 1: excessive intolerance of opposing views [syn: fanaticism,
         fanatism, zealotry]