Clam | Define Clam at Dictionary.com
n. bivalve mollusk, c.1500, in clam-shell, originally Scottish, apparently a particular use from Middle English clam "pincers, vice, clamp" (late 14c.), from Old English clamm "bond, fetter, grip, grasp," from Proto-Germanic *klam-"to press or squeeze together" (cf. Old High German klamma "cramp, fetter, constriction," German Klamm "a ...