The Collaborative International Dictionary
Pivot \Piv"ot\, n. [F.; prob. akin to It. piva pipe, F. pipe. See Pipe.]
A fixed pin or short axis, on the end of which a wheel or other body turns.
The end of a shaft or arbor which rests and turns in a support; as, the pivot of an arbor in a watch.
Hence, figuratively: A turning point or condition; that on which important results depend; as, the pivot of an enterprise.
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(Mil.) 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.
Pivot tooth (Dentistry), an artificial crown attached to the root of a natural tooth by a pin or peg.
Wikipedia
A pivot gun was a type of cannon mounted on a fixed central emplacement which permitted it to be moved through a wide horizontal arc. They were a common weapon aboard ships and in land fortifications for several centuries but became obsolete after the invention of gun turrets. By mounting a cannon on a pivot, a much wider arc of fire could be obtained than was possible with conventional carriage-mounted cannons. Unlike the latter, however, pivot guns were fixed in one place and could not easily be moved outside of their horizontal arc; they could thus only really be used in fixed positions such as in a fort or on a battleship.
There was no standard size of pivot gun, though they tended to be fairly substantial weapons. Like other cannons, they were muzzleloaders and could fire either shells or grapeshot (or other types of shot). Their calibers ranged from a few inches to the giant 11-inch Dahlgren guns used by the United States Navy in the mid-19th century.
Pivot guns had a major disadvantage in warfare: they were very difficult to protect in battle and were necessarily very exposed, as they lay close to the surface of a ship's deck and required an open field of view. In the late 19th century they were replaced by " disappearing guns" and ultimately by turrets, which enabled a broad arc of fire while providing the gunners with all-round protection from incoming fire.
Pivot guns should not be confused with swivel guns, a much smaller type of ordnance.
Category:Naval artillery
Usage examples of "pivot gun".
Roger nodded to the lieutenant and continued forward, to where Despreaux stood beside the pivot gun.
But the pivot gun was a long gunwith a barrel as long as one of the three-meter natives was talland it threw a fifteen-kilo solid shot.
The engineer closed his mind to the eerie sounds and struggled up the ladder to the engine-room hatch aft of the big seven-inch pivot gun.
But the pivot gun was a long gun -- with a barrel as long as one of the three-meter natives was tall -- and it threw a fifteen-kilo solid shot.
The schooner Jessup would be outfitted with a pivot gun and put into service as an armed supply vessel for the Union troops there.