flatfish

from WordNet (r) 3.0 (2006)

flatfish
    n 1: sweet lean whitish flesh of any of numerous thin-bodied
         fish; usually served as thin fillets
    2: any of several families of fishes having flattened bodies
       that swim along the sea floor on one side of the body with
       both eyes on the upper side

from The Collaborative International Dictionary of English v.0.48

Flatfish \Flat"fish`\, n. (Zool.)
   Any fish of the family {Pleuronectid[ae]}; esp., the winter
   flounder ({Pleuronectes Americanus}). The flatfishes have the
   body flattened, swim on the side, and have eyes on one side,
   as the flounder, turbot, and halibut. See {Flounder}.
   [1913 Webster] flat foot