The Collaborative International Dictionary of English v.0.48:

Shammy \Sham"my\, n. [F. chamious a chamois, shammy leather. See
   Chamois.]
   1. (Zool.) The chamois.
      [1913 Webster]

   2. A soft, pliant leather, prepared originally from the skin
      of the chamois, but now made also from the skin of the
      sheep, goat, kid, deer, and calf. See Shamoying.
      [Written also chamois, shamoy, and shamois.]
      [1913 Webster] Shamois

WordNet (r) 3.0 (2006):

shammy
    n 1: a soft suede leather formerly from the skin of the chamois
         antelope but now from sheepskin [syn: chamois, chamois
         leather, chammy, chammy leather, shammy, shammy
         leather]