The Collaborative International Dictionary of English v.0.48:
Sole \Sole\, n. [F. sole, L. solea; -- so named from its flat
shape. See Sole of the foot.] (Zool.)
(a) Any one of several species of flatfishes of the genus
Solea and allied genera of the family Soleidae,
especially the common European species (Solea
vulgaris), which is a valuable food fish.
(b) Any one of several American flounders somewhat resembling
the true sole in form or quality, as the California sole
(Lepidopsetta bilineata), the long-finned sole
(Glyptocephalus zachirus), and other species.
Lemon, or French, sole (Zool.), a European species of
sole (Solea pegusa).
Smooth sole (Zool.), the megrim.