shad

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of several food fishes of the genus Alosa, especially the North American species A. sapidissima, related to the herrings but atypical in swimming up streams from marine waters to spawn.

Century Dictionary and Cyclopedia

1. n. A clupeoid fish of the genus Alosa, in which there are no palatal teeth and the cheeks are deeper than they are long. The common shad of America, A. sapidissima, is one of the most important food-fishes along the Atlantic coast of the United States, and has lately been introduced on the Pacific coast. It is anadromous, ascending rivers to spawn. It is usually from 18 to 28 inches long, of stout compressed form, the body being comparatively deep. The color is silvery, becoming bluish on the back, with a dark spot behind the opercle, and sometimes several others along the line dividing the color of the back from the white of the sides. The mouth is large, the fins are comparatively small, and the dorsal is much nearer to the snout than to the base of the caudal fin. The shad is taken with the seine, and is highly esteemed for its excellent flavor. The British shad are of two species: the allice-shad, A. vulgaris, and the twaite, A. finta. The Chinese shad is A. reevesi.
2. n. In the Ohio valley, a clupeoid, Pomolobus chrysochloris, with persistent and well-developed teeth in the premaxillaries and front of the lower jaw.
3. n. With a qualifying word, one of several other fishes. See gizzard-shad, and phrases below.
4. n. A Middle English past participle of shed.

Wiktionary

1. n. Any one of several species of food fishes that comprise the genus Alosa in the family Clupeidae, to which the herrings also belong; river herring.

GNU Webster's 1913

1. n. (Zoöl.) Any one of several species of food fishes of the Herring family. The American species (Alosa sapidissima formerly Clupea sapidissima), which is abundant on the Atlantic coast and ascends the larger rivers in spring to spawn, is an important market fish. The European allice shad, or alose (Alosa alosa formerly Clupea alosa), and the twaite shad (Alosa finta formerly Clupea finta), are less important species.

WordNet 3.0

1. n. herring-like food fishes that migrate from the sea to fresh water to spawn
2. n. bony flesh of herring-like fish usually caught during their migration to fresh water for spawning; especially of Atlantic coast