What does stopcock mean?
A stopcock is a valve installed in a pipe or connected to a plumbing fixture to control the flow of water, gas, or another liquid. Its main practical use is to isolate a section of a system, allowing work to be carried out without continuing the flow throughout the pipework. The word is especially associated with plumbing, heating, and building maintenance, although it can describe valves in other piped systems as well. In everyday British English, a stopcock is often the small valve beneath or beside a sink or appliance that a person turns on or off. It should not be confused with a faucet, which is the fixture where water is dispensed, or with a general valve, which is a broader term. A stopcock is especially valuable in emergencies because it can stop the flow of water quickly and reduce the risk of flooding or further damage.
nounA valve fitted to a pipe or plumbing fixture, used to control or shut off the flow of liquid or gas. A stopcock is commonly used to isolate part of a water or heating system for maintenance.
- A valve in a pipe or plumbing system used to control or shut off the flow of water, gas, or another liquid.
"She turned the stopcock to shut off the water before repairing the pipe."
"The plumber closed the stopcock before replacing the leaking section of pipe."
"Check the stopcock on the radiator to make sure it is fully open."
The plural is formed by adding -s to the end of the word.
"All the stopcocks were closed before the building was inspected."
A stopcock is the small but essential control that lets plumbers stop the flow without dismantling an entire pipe.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does stopcock come from?
The word is a compound formed in English from stop and cock. In this compound, cock refers to a tap or valve controlling a flow, while stop indicates the function of interrupting that flow. The word has long been used in plumbing and related engineering contexts. The precise history of the word cock in its tap sense is less certain than the later development of stopcock, so it is best understood through the established compound rather than assigned an uncertain individual date.
Related word forms
How stopcock is actually used
The term is primarily used in plumbing, engineering, and building maintenance. It is especially common in British English, while the general term valve is widely used in both British and US English.
Easily confused with stopcock
A stopcock is an inline valve used to control flow within a pipe, whereas a faucet is the visible fixture from which water is drawn.
A spigot is usually an outdoor or utility tap, while a stopcock is specifically a valve that controls or isolates flow in a plumbing system.