Source : Webster's Revised Unabridged Dictionary (1913)

Ray \Ray\, n. [F. raie, L. raia. Cf. {Roach}.] (Zo["o]l.)
   (a) Any one of numerous elasmobranch fishes of the order
       Rai[ae], including the skates, torpedoes, sawfishes, etc.
   (b) In a restricted sense, any of the broad, flat,
       narrow-tailed species, as the skates and sting rays. See
       {Skate}.

   {Bishop ray}, a yellow-spotted, long-tailed eagle ray
      ({Stoasodon n[`a]rinari}) of the Southern United States
      and the West Indies.

   {Butterfly ray}, a short-tailed American sting ray
      ({Pteroplatea Maclura}), having very broad pectoral fins.
      

   {Devil ray}. See {Sea Devil}.

   {Eagle ray}, any large ray of the family {Myliobatid[ae]}, or
      {[AE]tobatid[ae]}. The common European species
      ({Myliobatis aquila}) is called also {whip ray}, and
      {miller}.

   {Electric ray}, or {Cramp ray}, a torpedo.

   {Starry ray}, a common European skate ({Raia radiata}).

   {Sting ray}, any one of numerous species of rays of the
      family {Trygonid[ae]} having one or more large, sharp,
      barbed dorsal spines on the whiplike tail. Called also
      {stingaree}.

Source : WordNet®

butterfly ray
     n : short-tailed broad-finned stingray