n. One who, or that which, plunges; a diver. A long solid cylinder, used, instead of a piston or bucket, as a forcer in pumps. One who bets heavily and recklessly on a race; a reckless speculator.
- (Pottery) A boiler in which clay is beaten by a wheel to a creamy consistence.
- (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.