The Collaborative International Dictionary of English v.0.48:

Sting ray \Sting ray\ or Stingray \Sting"ray`\, n.
   Any one of numerous rays of the family Dasyatidae, syn.
   Trygonidae, having one or more large sharp barbed dorsal
   spines, on the whiplike tail, capable of inflicting severe
   wounds. Some species reach a large size, and some, esp., on
   the American Pacific coast, are very destructive to oysters.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

stingray
    n 1: large venomous ray with large barbed spines near the base
         of a thin whiplike tail capable of inflicting severe wounds