Pivot

pivot
1. A fixed pin or short axis, on the end of which a wheel or other body turns.
2. The end of a shaft or arbor which rests and turns in a support; as, the pivot of an arbor in a watch.
3. Hence, figuratively: A turning point or condition; that on which important results depend; as, the pivot of an enterprise.
4. The officer or soldier who simply turns in his place whike the company or line moves around him in wheeling; called also pivot man. Pivot bridge, a form of drawbridge in which one span, called the pivot span, turns about a central vertical axis. Pivot gun, a gun mounted on a pivot or revolving carriage, so as to turn in any direction.
(Science: dentistry) Pivot tooth, an artificial crown attached to the root of a natural tooth by a pin or peg.
Origin: F.; prob. Akin to It. Piva pipe, F. Pipe. See Pipe.