The Collaborative International Dictionary of English v.0.48:

Shamanism \Sha"man*ism\, n.
   The type of religion which once prevalied among all the
   Ural-Altaic peoples (Tungusic, Mongol, and Turkish), and
   which still survives in various parts of Northern Asia. The
   Shaman, or wizard priest, deals with good as well as with
   evil spirits, especially the good spirits of ancestors.
   --Encyc. Brit.
   [1913 Webster]

WordNet (r) 3.0 (2006):

shamanism
    n 1: any animistic religion similar to Asian shamanism
         (especially as practiced by certain Native American tribes)
    2: an animistic religion of northern Asia having the belief that
       the mediation between the visible and the spirit worlds is
       effected by shamans [syn: shamanism, Asian shamanism]