drainplug
nounUK /ˈdreɪnplʌɡ/
US /ˈdreɪnplʌɡ/
A drainplug is a small cap that stops water from going down a hole.
She pulled out the drainplug so the dirty water could flow away.
OTHER MEANINGS
2. A threaded bolt used to close the oil drain hole in an engine or machine.
He removed the drainplug to let the old oil out of the car.
3. A removable plug at the bottom of a boat that lets water drain out.
Remember to put the drainplug back in before you launch the boat.
4. A cap that seals a drain in a pool or tank.
The pool drainplug was loose, so the water level kept dropping.