What is "jaw bit"

Jaw \Jaw\ (j[add]), n. [A modification of chaw, formed under the influence of F. joue the cheek. See Chaw, Chew.]

1. (Anat.)

   1. One of the bones, usually bearing teeth, which form the framework of the mouth.

   2. Hence, also, the bone itself with the teeth and covering.

   3. In the plural, the mouth.

2. Fig.: Anything resembling the jaw of an animal in form or action; esp., pl., the mouth or way of entrance; as, the jaws of a pass; the jaws of darkness; the jaws of death.
   --Shak.

3. (Mach.)

   1. A notch or opening.

   2. A notched or forked part, adapted for holding an object in place; as, the jaw of a railway-car pedestal. See Axle guard. (b) One of a pair of opposing parts which are movable towards or from each other, for grasping or crushing anything between them, as, the jaws of a vise, or the jaws of a stone-crushing machine.

4. (Naut.) The inner end of a boom or gaff, hollowed in a half circle so as to move freely on a mast.

5. Impudent or abusive talk. [Slang]
   --H. Kingsley.

   Syn: lip.

   Jaw bit (Railroad), a bar across the jaws of a pedestal underneath an axle box.

   Jaw breaker, a word difficult to pronounce. [Obs.]

   Jaw rope (Naut.), a rope which holds the jaws of a gaff to the mast.

   Jaw tooth, a molar or grinder; a back tooth.