plunger

Etymology

From plunge + -er.

noun

1. A device that is used to remove blockages from the drain of a basin or tub, by suction.
2. The internal piece of a syringe that pushes out or pulls in any contents.
3. The sliding activator of an exploder, an electrical generator used to trigger electrical detonators such as blasting caps.
4. The part of a cafetière that is pushed down to remove grounds from coffee.
5. One who plunges; a diver.
6. A horse that plunges, or throws itself suddenly forward.
7. (military) A cavalryman.
8. 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.
9. The moving portion of a solenoid.
10. (pinball) The spring-loaded assembly that propels the ball onto the table.
11. (dated, slang) A reckless gambler or gamble.
12. (pottery) A boiler in which clay is beaten by a wheel to a creamy consistency.
    Another part of the invention relates to making articles of earthenware by a plunger, which is forced into a mould 1862, Examples of the Architecture of the Victorian Age[…], (Please provide the book title or journal name)
13. (firearms) The firing pin of a breechloader.