piston

[ pis-tuh n ]
/ ˈpɪs tən /

noun

a disk or cylindrical part tightly fitting and moving within a cylinder, either to compress or move a fluid collected in the cylinder, as air or water, or to transform energy imparted by a fluid entering or expanding inside the cylinder, as compressed air, explosive gases, or steam, into a rectilinear motion usually transformed into rotary motion by means of a connecting rod.
a pumplike valve used to change the pitch in a cornet or the like.

Origin of piston

1695–1705; < French < Italian pistone piston, a learned alteration of pestone large pestle, equivalent to pest(are) to pound (variant of Medieval Latin pistare, derivative of Latin pīstus past participle of pīnsere to pound) + -one augmentative suffix
Related formspis·ton·like, adjectivesub·pis·ton, noun

Definition for piston (2 of 2)

Piston

[ pis-tuh n ]
/ ˈpɪs tən /

noun

Walter,1894–1976, U.S. composer.

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for piston

British Dictionary definitions for piston

piston

/ (ˈpɪstən) /

noun

a disc or cylindrical part that slides to and fro in a hollow cylinder. In an internal-combustion engine it is forced to move by the expanding gases in the cylinder head and is attached by a pivoted connecting rod to a crankshaft or flywheel, thus converting reciprocating motion into rotation

Word Origin for piston

C18: via French from Old Italian pistone, from pistare to pound, grind, from Latin pinsere to crush, beat
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Science definitions for piston

piston

[ pĭstən ]

A solid cylinder or disk that fits snugly into a hollow cylinder and moves back and forth under the pressure of a fluid (typically a hot gas formed by combustion, as in many engines), or moves or compresses a fluid, as in a pump or compressor.

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.