from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun Any of numerous freshwater and marine mollusks of the class Bivalvia, having a shell consisting of two hinged valves connected by a ligament, and including the clams, mussels, oysters, and scallops.
  • adjective Having a shell consisting of two hinged valves.
  • adjective Consisting of two similar separable parts.

from The Century Dictionary.

  • 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.
  • noun plural Folding doors.
  • noun In zoology, a headless lamellibranch mollusk whose shell has two hinged valves, which are opened and shut by appropriate muscles: opposed to univalve.
  • noun In botany, a pericarp in which the seed-case opens or splits into two parts.

from the GNU version of the Collaborative International Dictionary of English.

  • noun (Zoöl.) 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.
  • noun (Bot.) A pericarp in which the seed case opens or splits into two parts or valves.
  • adjective (Zoöl. & Bot.) Having two shells or valves which open and shut, as the oyster and certain seed vessels.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun 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 WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

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


from Wiktionary, Creative Commons Attribution/Share-Alike License

bi- (“two”) +‎ valve


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