STOPCOCK n.
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.
SUBSTANCE n.
stitutes anything what it is; real or existing essence. These cooks, how they stamp, and strain, and grind, And turn substance into accident! Chaucer. Heroic virtue did his actions guide, And he the substance, not the appearance, chose. Dryden.