stopcock; stop valve; shut-off valve
A valve used to stop the flow of water, typically in plumbing or water supply systems. Often refers to the main shut-off valve for a building or fixture.
Please close the stopcock before repairing the water pipe.
The shut-off valve for this building is in the basement.
Compound of 止水 (shisui, 'stopping water') + 栓 (sen, 'plug, stopper, valve').