toggle joint
    n 1: a joint made by two arms attached by a pivot; used to apply
         pressure at the two ends by straightening the joint

Toggle \Tog"gle\, v. t. (Computer programming)
   To change the value of (a program variable) by activating a
   toggle switch; as, to toggle the view from character to
   graphic mode; to toggle the keyboard input from insert to
   overtype mode.
   [PJC]

   Toggle iron, a harpoon with a pivoted crosspiece in a
      mortise near the point to prevent it from being drawn out
      when a whale, shark, or other animal, is harpooned.

   Toggle joint, an elbow or knee joint, consisting of two
      bars so connected that they may be brought quite or nearly
      into a straight line, and made to produce great endwise
      pressure, when any force is applied to bring them into
      this position.