Source : Webster's Revised Unabridged Dictionary (1913)

Jaw \Jaw\, n. [A modification of chaw, formed under the
   influence of F. joue the cheek. See {Chaw}, {Chew}.]
   1. (Anat.)
      (a) One of the bones, usually bearing teeth, which form
          the framework of the mouth.
      (b) Hence, also, the bone itself with the teeth and
          covering.
      (c) 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.)
      (a) A notch or opening.
      (b) 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.

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

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