Stopcock

Webster's Dictionary of the English Language

·noun The turning plug, stopper, or spigot of a faucet.

II. Stopcock ·noun A bib, faucet, or short pipe, fitted with a turning stopper or plug for permitting or restraining the flow of a liquid or gas; a cock or valve for checking or regulating the flow of water, gas, ·etc., through or from a pipe, ·etc.