1. (Science: marine biology, zoology) Any marine bivalve mollusk of the genus ostrea. They are usually found adhering to rocks or other fixed objects in shallow water along the seacoasts, or in brackish water in the mouth of rivers. The common European oyster (Ostrea edulis), and the American oyster (Ostrea Virginiana), are the most important species.
2. A name popularly given to the delicate morsel contained in a small cavity of the bone on each side of the lower part of the back of a fowl. Fresh water oyster a small crab (pinnotheres ostreum) which lives as a commensal in the gill cavity of the oyster. Oyster dredge, a rake or small dragnet of bringing up oyster from the bottom of the sea. Oyster fish. (Zool) The tautog. The toadfish. Oyster plant.
Origin: OF. Oistre, F. Huitre, L. Ostrea, ostreum,Gr.; prob. Akin to bone, the oyster being so named from its shell. Cf. Osseous, Ostracize.