The Collaborative International Dictionary of English v.0.48:

Iconoclasm \I*con"o*clasm\, n. [Cf. F. iconoclasme. See
   Iconoclast.]
   The doctrine or practice of the iconoclasts; image breaking.
   [1913 Webster]

WordNet (r) 3.0 (2006):

iconoclasm
    n 1: the orientation of an iconoclast