(klam) noun
1. Any of various bivalve mollusks; especially, the edible quahog of North Atlantic American coasts, and the long or soft clam (Mya arenaria) of the southern Atlantic coasts.
2. U.S. Colloq. An uncommunicative person.
—giant clam A huge bivalve mollusk (Tridacna gigas) of the Indian and Pacific Oceans: the shell may exceed 3 feet in length and weigh more than 500 pounds.
—v.i. clammed, clam·ming to hunt for or dig clams.
—to clam up U.S. Slang To maintain silence, as a criminal under interrogation. [Short for clamshell <clam a clamp, OE clamm + SHELL]
GIANT CLAM

(klam) Brit. Dial. v.t.
To smear with a sticky substance; glue or stick: to clam paper to the wall.
—v.i. To be sticky or clammy; be damp or cold.
—adjective Sticky.
—noun
1. Clamminess; cold dampness.
2. A sticky substance. [Cf. OE clœman smear, Du. klam sticky]

(klam) noun
A clamp, as of bricks. [OE clamm grip, grasp]

(klam) Brit. noun
The simultaneous ringing of all the bells in a chime; hence, clangor; clamor.
—v.i.
1. To ring all the bells of a chime together.
2. To muffle or jangle a bell. [Imit.]