noun

• A device that is used to remove blockages from the drain of a basin or tub, by suction.
• The internal piece of a syringe that pushes out or pulls in any contents.
• The sliding activator of an exploder, an electrical generator used to trigger electrical detonators such as blasting caps.
• Certain equipment for brewing coffee.
• The part of a cafetière that is pushed down to remove grounds from coffee.
• A cafetière, through abbreviation of coffee plunger.
• One who plunges; a diver.
• A horse that plunges, or throws itself suddenly forward.
• (military) A cavalryman.
• A device similar to a piston but without a mechanism; a long solid cylinder used, instead of a piston or bucket, as a forcer in pumps.
• The moving portion of a solenoid.
• (pinball) The spring-loaded assembly that propels the ball onto the table.
• (dated, slang) A reckless gambler or gamble.
• (pottery) A boiler in which clay is beaten by a wheel to a creamy consistency.
• (firearms) The firing pin of a breechloader.