Stopcock
/ˈstɑːpkɑːk/
Definition 1 of 1
Pro Tip 1/3Plumbing Situations
Stopcock is commonly used when discussing plumbing to control water flow. 
The plumber instructed me to find the main stopcock to stop the leak.
Pro Tip 2/3Emergency Use
Knowing how to operate a stopcock is crucial in emergencies to prevent water damage. 
During the flood, we turned off the stopcock to avoid more water coming in.
Pro Tip 3/3Technical Context
The word is mostly used in technical or mechanical contexts, not in everyday conversation. 
The technician checked the stopcock to ensure the system was not leaking.