any of numerous species of large marine molluscs living in sand or mud, many of which are eaten as food, having a burrowing foot and noted for tightly closing the two halves of its shell: class Bivalvia
a marine mollusc eaten as food, having a burrowing foot and noted for tightly closing the two halves of its shell
[Old English clamm bond, fetter; from the clamping action of the shells]