Bivalve

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.
Historical Examples

Encyclopaedia Britannica, 11th Edition, Volume 16, Slice 6 Various
The Sailor’s Word-Book William Henry Smyth
The Sea Shore William S. Furneaux
On the Genesis of Species St. George Mivart
A Breeze from the Woods, 2nd Ed. William Chauncey Bartlett
A Conchological Manual George Brettingham Sowerby
Chambers’s Twentieth Century Dictionary (part 1 of 4: A-D) Various
A Conchological Manual George Brettingham Sowerby
The New Gresham Encyclopedia Various
Lachesis Lapponica Carl von Linn

noun
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
adjective
Also pelecypod, lamellibranch. of, relating to, or belonging to the Pelecypoda
(biology) Also bivalvate (baɪˈvælveɪt). having or consisting of two valves or similar parts: a bivalve seed capsule
adj.
bivalve
(bī’vālv’)
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.