D defs.my
Entry 5 senses Webster, 1913

Plunger

/plŭn'-jẽr/ · Plun·ger · IPA /ˈplʌnd͡ʒɚ/
01 n. One who, or that which, plunges; a diver.
  1. 1.
    One who, or that which, plunges; a diver.
  2. 2.
    A long solid cylinder, used, instead of a piston or bucket, as a forcer in pumps.
  3. 3.
    One who bets heavily and recklessly on a race; a reckless speculator.[Cant]
  4. 4.
    A boiler in which clay is beaten by a wheel to a creamy consistence.(Pottery)
  5. 5.
    The firing pin of a breechloader.(Gun.)
Phrases & compounds
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