FLOUNDER, a name given generally to flat fishes, other than soles, and in England particularly to Pleuronectes flesus, which range from northern Europe to the Mediterranean, and often enter fresh water. P. stellatus of the Pacific coast of North America is a related species. In America the name is given to several species of flat fish, e.g., the winter flounder (Pseudo pleuronectes americanus) and the summer flounder (Paralichthys dentatus).