Source : Webster's Revised Unabridged Dictionary (1913)

Throttle \Throt"tle\, n. [Dim. of throat. See {Throat}.]
   1. The windpipe, or trachea; the weasand. --Sir W. Scott.

   2. (Steam Engine) The throttle valve.

   {Throttle lever} (Steam Engine), the hand lever by which a
      throttle valve is moved, especially in a locomotive.

   {Throttle valve} (Steam Engine), a valve moved by hand or by
      a governor for regulating the supply of steam to the steam
      chest. In one form it consists of a disk turning on a
      transverse axis.

Source : WordNet®

throttle valve
     n : a valve that regulates the supply of fuel to the engine
         [syn: {accelerator}, {throttle}]