The Collaborative International Dictionary of English v.0.48:

Shedder \Shed"der\, n.
   1. One who, or that which, sheds; as, a shedder of blood; a
      shedder of tears.
      [1913 Webster]

   2. (Zool.) A crab in the act of casting its shell, or
      immediately afterwards while still soft; -- applied
      especially to the edible crabs, which are most prized
      while in this state.
      [1913 Webster]

WordNet (r) 3.0 (2006):

shedder
    n 1: an attacker who sheds or spills blood; "a great hunter and
         spiller of blood" [syn: shedder, spiller]