from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. A mollusk, such as an oyster or a clam, that has a shell consisting of two hinged valves.
  • adj. Having a shell consisting of two hinged valves.
  • adj. Consisting of two similar separable parts.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. Any mollusc belonging to the taxonomic class Bivalvia, characterized by a shell consisting of two hinged sections, such as a scallop, clam, mussel or oyster.

from the GNU version of the Collaborative International Dictionary of English

  • adj. Having two shells or valves which open and shut, as the oyster and certain seed vessels.
  • n. A mollusk having a shell consisting of two lateral plates or valves joined together by an elastic ligament at the hinge, which is usually strengthened by prominences called teeth. The shell is closed by the contraction of two transverse muscles attached to the inner surface, as in the clam, -- or by one, as in the oyster. See Mollusca.
  • n. A pericarp in which the seed case opens or splits into two parts or valves.

from The Century Dictionary and Cyclopedia

  • Having two leaves or folding parts: as, a bivalve speculum.
  • In zoology, having two shells united by a hinge.
  • In botany, having two valves, as a seed-case.
  • n. plural Folding doors.
  • n. In zoology, a headless lamellibranch mollusk whose shell has two hinged valves, which are opened and shut by appropriate muscles: opposed to univalve.
  • n. In botany, a pericarp in which the seed-case opens or splits into two parts.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. marine or freshwater mollusks having a soft body with platelike gills enclosed within two shells hinged together
  • adj. used of mollusks having two shells (as clams etc.)


bi- (“two”) +‎ valve (Wiktionary)



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