Pronunciation: (bī'valv"),[key] —n. Also called lamellibranch.Zool.any mollusk, as the oyster, clam, scallop, or mussel, of the class Bivalvia, having two shells hinged together, a soft body, and lamellate gills.
—adj. 1. Bot.having two valves, as a seedcase.
2. Zool.having two shells, usually united by a hinge.
3. having two similar parts hinged together.