<p><strong>Noun</strong></p><ul><li>any mollusk of the class Pelecypoda (Lamellibranchiata), characterized by a bivalve shell enclosing the headless body and lamellate gills, comprising the oysters, clams, mussels, and scallops.</li><li>any of several other trees having bitter-tasting wood.</li></ul><p><strong>Adjective</strong></p><ul><li>belonging or pertaining to the Pelecypoda.</li></ul>