Source : Webster's Revised Unabridged Dictionary (1913)

Haddock \Had"dock\, n. [OE. hadoc, haddok, of unknown origin;
   cf. Ir. codog, Gael. adag, F. hadot.] (Zo["o]l.)
   A marine food fish ({Melanogrammus [ae]glefinus}), allied to
   the cod, inhabiting the northern coasts of Europe and
   America. It has a dark lateral line and a black spot on each
   side of the body, just back of the gills. Galled also
   {haddie}, and {dickie}.

   {Norway haddock}, a marine edible fish ({Sebastes marinus})
      of Northern Europe and America. See {Rose fish}.

Source : WordNet®

Melanogrammus aeglefinus
     n : important food fish on both sides of the Atlantic; related
         to cod but usually smaller [syn: {haddock}]