Plun·ger n.
 1. One who, or that which, plunges; a diver.
 2. A long solid cylinder, used, instead of a piston or bucket, as a forcer in pumps.
 3. One who bets heavily and recklessly on a race; a reckless speculator. [Cant]
 4. Pottery A boiler in which clay is beaten by a wheel to a creamy consistence.
 5. Gun. The firing pin of a breechloader.
 Plunger bucket, a piston, without a valve, in a pump.
 Plunger pole, the pump rod of a pumping engine.
 Plunger pump, a pump, as for water, having a plunger, instead of a piston, to act upon the water. It may be single-acting or double-acting

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