halibut, n. [OE. hali holy + but, butte, flounder; akin to D. bot, G. butte; cf. D. heilbot, G. heilbutt. So named as being eaten on holidays. See Holy, Holiday.].
A large, northern, marine flatfish (Hippoglossus vulgaris), of the family Pleuronectidæ. It often grows very large, weighing more than three hundred pounds. It is an important food fish. [1913 Webster]