piston

noun pis·ton \ ˈpi-stən \

Updated on: 11 Sep 2017

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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See piston defined for kids

Recent Examples of piston from the Web

Once the latter was created, the piston-engine helicopter became moot.

— bonnie l. cook, Philly.com, "Rens H. Swan, 90, engineer on Boeing team that developed the Chinook helicopter," 29 Aug. 2017
Day 2 coring the Miss. River Delta Front: recovering a long piston core.

— sara sneath, NOLA.com, "A submarine sank this ship in the Gulf in 1942; now it's studied for mudslides: report," 24 Aug. 2017
Care and maintenance are as simple as wiping the gun off and applying a dab of oil instead of worrying about gas pistons, forearm nuts or recoil springs.

— author: christine cunningham, Alaska Dispatch News, "Gearing up for another bird-hunting season in Alaska," 16 Aug. 2017
Tate, the defending Seafair champion, drove the U-9 Les Schwab Tires to a win in Heat 1B. Jimmy King in the U-3 Grigg’s Ace Hardware, the only piston-powered boat in the turbine fleet, was second.

— seattle times staff, The Seattle Times, "Jimmy Shane, Andrew Tate win first heat at Columbia Cup," 29 July 2017
The mechanic later showed me the piston and it was destroyed.

— Ramona Sentinel, "Jan Ryan re-elected to Realtors trade group board," 21 July 2017
Since a track-day car that goes like hell and doesn't stop is a car that crashes, Chevy fits huge 15.4-inch (391mm) brake rotors in front with six-piston Brembo calipers that use every millimeter of space inside the 19-inch diameter wheel.

— jim resnick, Ars Technica, "Camaro goes nuclear: Chevrolet escalates the muscle car war," 18 July 2017
CELTICS TRADE BRADLEY TO PISTONS The Detroit Pistons traded forward Marcus Morris to Boston for guard Avery Bradley and a second-round draft pick in 2019.

— New York Times, "F.B.I. Investigated Bob Knight Over Women’s Complaints," 8 July 2017
The high-performance braking system brings all that go to a whoa in a hurry, thanks to six-piston front brake calipers and four-piston rears.

— star-telegram, "An Exuberant Spirit: The all-new Lexus LC 500 exudes luxurious edginess," 5 July 2017

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

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