The Collaborative International Dictionary of English v.0.48:

Crampon \Cram"pon\ (kr[a^]m"p[o^]n), n. [F. See Crampoons.]
   1. (Bot.) An a["e]rial rootlet for support in climbing, as of
      ivy.
      [1913 Webster]

   2. a device with pointed metal projections worn over the
      shoes to provide traction when walking over ice, or in
      mountaineering; -- usually used in the plural.
      [PJC]

   3. same as crampoon.
      [PJC]

WordNet (r) 3.0 (2006):

crampon
    n 1: a hinged pair of curved iron bars; used to raise heavy
         objects [syn: crampon, crampoon]
    2: an iron spike attached to the shoe to prevent slipping on ice
       when walking or climbing [syn: crampon, crampoon,
       climbing iron, climber]