piston

noun pis·ton \ ˈpi-stən \

|Updated on: 25 Jul 2018

Definition of piston

1 : a sliding piece moved by or moving against fluid pressure which usually consists of a short cylindrical body fitting within a cylindrical chamber or vessel along which it moves back and forth

2 : a sliding valve moving in a cylinder in a brass instrument which when depressed by a finger knob serves to lower the instrument's pitch

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Recent Examples of piston from the Web

His powerful muscles seemed to uncoil, and his shoulders, like oversize pistons, drove us forward, springing over the sand as though a 160-pound man weren’t on his back.

— peter gwin, WSJ, "The Horses That Changed History," 19 June 2018
But at age 93, even Kelly, one of the pistons in the long-ago Daley machine, can’t get a park named in his honor.

— morgan greene, chicagotribune.com, "Why a ward boss in the Daley machine is having a hard time getting a park named for him," 8 June 2018
The engine-rebuild kit—including pistons, rings, bearings, oil pump, and timing belt—was $245.

— Car and Driver, "The Battle of the Off-Road Beaters: Ford F-150 Custom vs. Geo Tracker, Jeep Cherokee, Land Rover Discovery," 30 Nov. 2016
Smaller piston skirts cut 27 grams while the connecting rods are 41 grams lighter.

— jeff yip, Houston Chronicle, "2019 Mazda MX-5 gets 26-hp boost," 23 June 2018
Up against a wall in the Amber Lab is a robot that bounces up and down a scaffolding like a piston.

— matt simon, WIRED, "Inside the Mad Lab That's Getting Robots to Walk and Jump Like Us," 14 June 2018
In one of the most ferocious performances of the night, Christiana Perrault pistons her hips in a black fringe miniskirt cut to the moon as Turner.

— andrea simakis, cleveland.com, "'The Royale,' inspired by boxer Jack Johnson, brings fight for freedom to stage (preview)," 13 May 2018
The volume the piston can squeeze is the compression ratio.

— blake z. rong, Popular Mechanics, "The Evolution of the Combustion Engine," 5 June 2018
High-flow exhaust, stronger pistons and a new cold-air intake make for an engine that can better endure extended track sessions.

— robert duffer, chicagotribune.com, "2018 Subaru WRX STi Type RA boggles the mind as most expensive Subaru," 30 May 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'piston.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Origin and Etymology of piston

French, from Italian pistone, from pistare to pound, from Old Italian, from Medieval Latin, from Latin pistus, past participle of pinsere to crush — more at pestle

NEW! Time Traveler

First Known Use: 1704

in the meaning defined at sense 1

See Words from the same year

Piston

biographical name Pis·ton \ ˈpi-stən \

Definition of Piston

Walter Hamor 1894–1976 American composer

PISTON Defined for English Language Learners

piston

noun

Definition of piston for English Language Learners

: a part of an engine that moves up and down inside a tube and that causes other parts of the engine to move

PISTON Defined for Kids

piston

noun pis·ton \ ˈpi-stən \

Definition of piston for Students

: a disk or short cylinder that slides back and forth inside a larger cylinder and is moved by steam in steam engines and by the explosion of fuel in automobiles