plug-cock

Century Dictionary and Cyclopedia

1. n. A cock in which a plug with a transverse hole in it is fitted into a transverse hole in a hollow barrel or cylinder, the diameter of the plug being greater than the interior diameter of the cylinder, and therefore permitting liquid to flow through the latter only when the transverse hole in the plug is so turned as to form a continuous passage with the hollow in the cylinder. The plugs are sometimes covered or packed with a yielding material, and are usually tapered, so that pressing them into their seats keeps them tight.