Plunger

n.	1.	One who, or that which, plunges; a diver.
	2.	A long solid cylinder, used, instead of a piston or bucket, as a forcer in pumps.
	3.	One who bets heavily and recklessly on a race; a reckless speculator.
	4.	(Pottery) A boiler in which clay is beaten by a wheel to a creamy consistence.
	5.	(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

Noun	1.	plunger - someone who risks losses for the possibility of considerable gains Synonyms: speculator
	2.	plunger - someone who dives (into water) Synonyms: diver
	3.	plunger - hand tool consisting of a stick with a rubber suction cup at one end; used to clean clogged drains Synonyms: plumber's helper
	4.	plunger - mechanical device that has a plunging or thrusting motion Synonyms: piston

adventurer, betting ring, bettor, big operator, boneshaker, cardshark, cardsharp, cardsharper, compulsive gambler, crap shooter, deep-sea diver, diver, free diver, frogman, gambler, gamester, gunslinger, hazarder, jumper, lame duck, margin purchaser, operator, parachute jumper, pearl diver, petty gambler, piker, player, punter, scalper, scuba diver, sharp, sharper, sharpie, skin diver, sky diver, smart operator, snorkel diver, speculator, sport, sporting man, sportsman, stag, tinhorn, tipster, tout, venturer, wagerer