Word Study
haddock
CIDE DICTIONARY
haddock, n. [OE. hadok, haddok, of unknown origin; cf. Ir. codog, Gael. adag, F. hadot.].
A marine food fish (Melanogrammus æglefinus ), 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 . [1913 Webster]
OXFORD DICTIONARY
haddock, n. (pl. same) a marine fish, Melanogrammus aeglefinus, of the N. Atlantic, allied to cod, but smaller.
Etymology
ME, prob. f. AF hadoc, OF (h)adot, of unkn. orig.
For further exploring for "haddock" in Webster Dictionary Online