ball cock

American  

Or ballcock

noun

1. a device for regulating the supply of water in a tank, cistern, or the like, consisting essentially of a valve connected to a hollow floating ball which by its rise or fall shuts or opens the valve.

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ball cock British  

noun

1. a device for regulating the flow of a liquid into a tank, cistern, etc, consisting of a floating ball mounted at one end of an arm and a valve on the other end that opens and closes as the ball falls and rises with the water level in the cistern

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Etymology

Origin of ball cock

First recorded in 1780–90

Example Sentences

To prevent their freezing when full of water, preserve a little circulation by leaving the cock dripping; or by tying up the ball cock during the winter's frost, the water may be preserved for use.

From The Cook and Housekeeper's Complete and Universal Dictionary; Including a System of Modern Cookery, in all Its Various Branches, Adapted to the Use of Private Families by Eaton, Mary, fl. 1823-1849

On top of the generator is a tipping water-bucket I supplied with water through a ball cock.

From Acetylene, the Principles of Its Generation and Use A Practical Handbook on the Production, Purification, and Subsequent Treatment of Acetylene for the Development of Light, Heat, and Power by Leeds, F. H. (Frank Henley)