Definition of plunger

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