plunger

plural plungers

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. Certain equipment for brewing coffee.
   1. The part of a cafetière that is pushed down to remove grounds from coffee.
   2. A cafetière, through abbreviation of coffee plunger.
5. One who plunges; a diver.
6. A horse that plunges, or throws itself suddenly forward.
7. governmentA 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. pinballThe spring-loaded assembly that propels the ball onto the table.
11. datedslangA reckless gambler or gamble.

    Well I suppose there's not one of you gentlemen here who hasnt^([sic]) at some time or other taken a plunger, and how many of you hasnt^([sic]) come back sadder and wiser.

    1925, John Dos Passos, Manhattan Transfer, New York, N.Y.; London: Harper & Brothers, →OCLC, 2nd section, page 146

12. potteryA 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. engineeringThe firing pin of a breechloader.