Meaning of PISTON in English

PISTON

ˈpistən noun

( -s )

Etymology: French, from Middle French, large pestle, from Old Italian pistone, from pistare to beat, pound, trample down (from Medieval Latin pistare, from Latin pistus, past participle of pinsere to pound, crush) + -one, aug. suffix — more at pestle

1. : a sliding piece moved by or moving against fluid pressure and usually consisting of a short cylinder fitting within a cylindrical vessel along which it moves back and forth — compare cylinder 2b,2c, slide valve

2.

a. or piston valve : a sliding valve moving in a cylinder like an engine piston in a brass wind instrument and serving when depressed by a finger knob to add a crook to the tube and hence to lower its pitch

b. or piston knob : a push button on an organ console for bringing in a preselected registration

Webster's New International English Dictionary.      Новый международный словарь английского языка Webster.