The Collaborative International Dictionary of English v.0.48:
Clamp \Clamp\ (kl[a^]mp), n. [Cf. LG. & D. klamp, Dan. klampe,
also D. klampen to fasten, clasp. Cf. Clamber, Cramp.]
1. Something rigid that holds fast or binds things together;
a piece of wood or metal, used to hold two or more pieces
(a) An instrument with a screw or screws by which work is
held in its place or two parts are temporarily held
(b) (Joinery) A piece of wood placed across another, or
inserted into another, to bind or strengthen.
3. One of a pair of movable pieces of lead, or other soft
material, to cover the jaws of a vise and enable it to
grasp without bruising.
4. (Shipbuilding) A thick plank on the inner part of a ship's
side, used to sustain the ends of beams.
5. A mass of bricks heaped up to be burned; or of ore for
roasting, or of coal for coking.
6. A mollusk. See Clam. [Obs.]
Clamp nails, nails used to fasten on clamps in ships.