Definition of: plunger

(plun′jər) noun
1. One who or that which plunges; a heavy or reckless speculator.
2. Mech. Any appliance having or adapted for a plunging motion, as the piston of a pump.
3. A cuplike device made of rubber and attached to a stick, used to clean out clogged drains, etc.: also called plumber's friend.