an aquatic mollusk that has a compressed body enclosed within a hinged shell, such as oysters, clams, mussels, and scallops. Also called pelecypod or lamellibranch.
- Class Bivalvia (formerly Pelecypoda or Lamellibranchia)
adjective (also bivalved) Zoology
(of a mollusk or other aquatic invertebrate) with a hinged shell. Botany having two valves.