Definition of piston valve in English:

piston valve

noun

  • 1A valve in a piston, as in that of a piston pump.

  • 2A valve consisting of a small piston sliding back and forth in a tube, opening or closing a hole or holes in the tube wall, as alongside the cylinder of a steam engine or in a brass musical instrument.

Origin

Mid 18th century; earliest use found in Martin Clare (d. 1751).