used of mollusks having two shells (as clams etc.)
source: WordNet 3.0
Having two shells or valves which open and shut, as the oyster and certain seed vessels.
source: Webster 1913
noun
marine or freshwater mollusks having a soft body with platelike gills enclosed within two shells hinged together
source: WordNet 3.0
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.
