Source : Webster's Revised Unabridged Dictionary (1913)

Dogfish \Dog"fish`\, n. (Zo["o]l.)
   1. A small shark, of many species, of the genera {Mustelus},
      {Scyllium}, {Spinax}, etc.

   Note: The European spotted dogfishes ({Scyllium catudus}, and
         {S. canicula}) are very abundant; the American smooth,
         or blue dogfish is {Mustelus canis}; the common picked,
         or horned dogfish ({Squalus acanthias}) abundant on
         both sides of the Atlantic.

   2. The bowfin ({Amia calva}). See {Bowfin}.

   3. The burbot of Lake Erie.

Source : WordNet®

dogfish
     n 1: primitive long-bodies carnivorous freshwater fish with a
          very long dorsal fin; found in sluggish waters of North
          America [syn: {bowfin}, {grindle}, {Amia calva}]
     2: any of several small sharks
     [also: {dogfishes} (pl)]