- Also called lamellibranch. Zoology. any mollusk, as the oyster, clam, scallop, or mussel, of the class Bivalvia, having two shells hinged together, a soft body, and lamellate gills.
- Botany. having two valves, as a seedcase.
- Zoology. having two shells, usually united by a hinge.
- having two similar parts hinged together.
- Also: pelecypod, lamellibranch any marine or freshwater mollusc of the class Pelecypoda (formerly Bivalvia or Lamellibranchia), having a laterally compressed body, a shell consisting of two hinged valves, and gills for respiration. The group includes clams, cockles, oysters, and mussels
- Also: pelecypod, lamellibranch of, relating to, or belonging to the Pelecypoda
- Also: bivalvate (baɪˈvælveɪt) biology having or consisting of two valves or similar partsa bivalve seed capsule
- Any of various mollusks of the class Bivalvia, having a shell consisting of two halves hinged together. Clams, oysters, scallops, and mussels are bivalves. The class Bivalvia is also called Pelecypoda, and was formerly called Lamellibranchia. Compare univalve.