cylinder

noun

cyl·​in·​der ˈsi-lən-dər 

1

a

: the surface traced by a straight line moving parallel to a fixed straight line and intersecting a fixed planar closed curve

b

: a solid or surface bounded by a cylinder and two parallel planes cutting all its elements

especially : right circular cylinder see Volume Formulas Table

2

: a cylindrical body or space: such as

a

: the turning chambered breech of a revolver

b(1)

: the piston chamber in an engine

(2)

: a chamber in a pump from which the piston expels the fluid

c

: any of various rotating members in a press (such as a printing press)

especially : one that impresses paper on an inked form

d

: a cylindrical clay object inscribed with cuneiform inscriptions

cylindered

ˈsi-lən-dərd 

adjective

Phrases

on all cylinders

: with maximum effort or intensity : at full capacity or speed

the economy is running on all cylinders

Examples of cylinder in a Sentence

the cylinder of a revolver

Recent Examples on the Web

The same process reduces a cylinder to a line and a doughnut to a circle. —Quanta Magazine, 31 Mar. 2025

By contrast, a similarly-sized solid cylinder showed no measurable voltage at any orientation. —The Physics Arxiv Blog, Discover Magazine, 24 Mar. 2025

The training phase is a gargantuan computational effort—Open AI supposedly used over 25,000 Nvidia Ampere 100 GPUs running on all cylinders for 100 days. —Ars Technica, 24 Mar. 2025

The lawsuit also claims that about two weeks before Sampson's death, Campbell-Alexander and another employee discovered a cylinder that locks and holds riders into their seats was overheating when the ride was operating. —Jeanine Santucci, USA TODAY, 20 Mar. 2025

Word History

Etymology

Middle French or Latin; Middle French cylindre, from Latin cylindrus, from Greek kylindros, from kylindein to roll; perhaps akin to Greek kyklos wheel — more at wheel

First Known Use

1570, in the meaning defined at sense 1a

Phrases Containing cylinder

• cylinder head
• cylinder seal
• graduated cylinder
• right circular cylinder
• vascular cylinder

Kids Definition

cylinder

noun

cyl·​in·​der ˈsil-ən-dər 

1

: a geometric shape composed of two parallel faces of identical size and shape (as circles) and a curved surface that completely connects their borders

2

: a body (as the piston chamber of an engine, the barrel of a pump, or the part of a revolver which holds the cartridges) shaped like a cylinder

cylindrical

sə-ˈlin-dri-kəl

adjective

cylindrically

-dri-k(ə-)lē

adverb