Definitions for "Flatfish"
Any fish of the family Pleuronectidæ; 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.
Laterally compressed benthic fishes of the order Pleuronectifomes, including flounders, soles, and tonguefishes.
A species of fish (including flounder, halibut and sole) characterized by a rather flat body, with both eyes located on the upper side. Flatfish swim on one side only; the side facing downwards is always very pale.