Throttle  —n. 1 a valve controlling the flow of fuel or steam etc. In an engine. B (in full throttle-lever) lever or pedal operating this valve. 2 throat, gullet, or windpipe. —v. (-ling) 1 choke or strangle. 2 prevent the utterance etc. Of. 3 control (an engine or steam etc.) With a throttle.  throttle back (or down) reduce the speed of (an engine or vehicle) by throttling. [perhaps from *throat]