|phylum of worms comprised of parasitic and free-living nonparasitic species|
|animal phylum comprised of sponges|
|1.||pelecypod, Also: 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|
|2.||pelecypod, Also: lamellibranch of, relating to, or belonging to the Pelecypoda|
|3.||biology Also: bivalvate having or consisting of two valves or similar parts: a bivalve seed capsule|
|bivalve (bī'vālv') Pronunciation Key
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.