piston

noun pis·ton \ ˈpi-stən \

Updated on: 19 Apr 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

See piston defined for English-language learners

See piston defined for kids

Recent Examples of piston from the Web

The four-piston, 13.8-inch Brembo front brakes have genuine brake ducts bringing cooling air to them under strenuous driving.

— jim resnick, Ars Technica, "America finally gets Honda’s best: The 2018 Civic Type R," 22 Jan. 2018
To swim, SoFi's motor pumps water into two balloon-like chambers in its tail, which function like a set of pistons in an engine.

— david grossman, Popular Mechanics, "MIT's Robot Fish Can Blend in and Spy on Real Sea Creatures," 21 Mar. 2018
Its window wipers come from a factory in Matamoros, some of its wheels from Chihuahua, and some of the pistons in its engine from Ramos Arizpe.

— ana swanson, New York Times, "Trump Trade Sanctions Aimed at China Could Ensnare Canada," 25 Feb. 2018
Brembo brakes all around have four-piston front calipers with 13.8-inch vented discs and 13.4 inches rear.

— mark maynard, sandiegouniontribune.com, "2018 Kia Stinger GT: A switchblade of change," 19 Jan. 2018
Finnish ship-engine maker Wartsila Corp. is aggressively hawking a new piston-engine—similar in design to the engine that powers automobiles—for power generation.

— russell gold, WSJ, "Siemens Pins Hopes on Small Gas Turbines," 16 Mar. 2018
Braking is absolute from 14-inch vented front discs with four-piston calipers and vented 13-inch rear discs — and the force awakens when halting a speeding 5,000-pound LS hybrid.

— mark maynard, sandiegouniontribune.com, "2018 Lexus LS 500h: From flagship to starship," 2 Mar. 2018
For Buffett, those are the fundamentals, the twin pistons that power stocks.

— shawn tully, Fortune, "Here's What 1999 Warren Buffett Might Say About the 2018 Stock Market," 14 Feb. 2018
Instead of opting for a retractable roof — partly because of snow and wind concerns — the firm designed five side-to-side mammoth glass doors that rotate on hydraulic pistons.

— joe gose, New York Times, "Super Bowl’s Minneapolis Stadium Brings a Surge in Development," 23 Jan. 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

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