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• cog
  cog

  noun

  a gear tooth, formerly especially one of hardwood or metal, fitted into a slot in a gearwheel of less durable material.
• cog.
  cog.

  abbreviation

  cognate.

cog

¹ American  

[kog, kawg] / kɒg, kɔg /

noun

1. a gear tooth, formerly especially one of hardwood or metal, fitted into a slot in a gearwheel of less durable material.

2. a cogwheel.

3. a person who plays a minor part in a large organization, activity, etc..

   He's just a small cog in the financial department.

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verb (used without object)

cogged, cogging

1. (of an electric motor) to move jerkily.

verb (used with object)

cogged, cogging

1. to roll or hammer (an ingot) into a bloom or slab.

idioms

1. slip a cog, to make a blunder; err.

   One of the clerks must have slipped a cog.

cog ² American  

[kog, kawg] / kɒg, kɔg /

verb (used with object)

cogged, cogging

1. to manipulate or load (dice) unfairly.

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verb (used without object)

cogged, cogging

1. to cheat, especially at dice.

cog ³ American  

[kog, kawg] / kɒg, kɔg /

noun

1. Carpentry. (in a cogged joint) the tongue in one timber, fitting into a corresponding slot in another.

2. Mining. a cluster of timber supports for a roof.

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verb (used with or without object)

cogged, cogging

1. Carpentry. to join with a cog.

cog. ⁴ American  

abbreviation

1. cognate.

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cog ¹ British  

/ kɒɡ /

noun

1. any of the teeth or projections on the rim of a gearwheel or sprocket

2. a gearwheel, esp a small one

3. a person or thing playing a small part in a large organization or process

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verb

1. (tr) metallurgy to roll (cast-steel ingots) to convert them into blooms

cog ² British  

/ kɒɡ /

noun

1. a tenon that projects from the end of a timber beam for fitting into a mortise

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verb

1. (tr) to join (pieces of wood) with cogs

cog ³ British  

/ kɒɡ /

verb

1. slang to cheat (in a game, esp dice), as by loading a dice

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cog More Idioms  

More idioms and phrases containing cog

• slip a cog

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Etymology

Origin of cog¹

First recorded in 1200–50; Middle English cogge, probably from a North Germanic language; compare Swedish kugge, Norwegian kugg “cog”; akin to German Kugel “bullet, ball, shot,” Old English cycgel ( see cudgel ( def. ))

Origin of cog²

First recorded in 1525–35; origin uncertain

Origin of cog³

1855–60; special use of cog ¹; replacing cock in same sense, special use of cock ¹ (in sense of projection); see coak

Explanation

An engine needs each of its parts to work. It has gears which have wheels. Each wheel has cogs, or tiny teeth that fit together, making the wheel turn, the engine run. Every cog is essential to that engine. People can also be cogs — they are the workers who, day in and day out, perform their duties seemingly with no end in sight. Feeling disheartened, they might say, "I'm just a cog in the system." If you hear this, remind them of the true definition of the term cog — an instrumental part of the whole.

Example Sentences

See Examples For:

cog cog. cogged cogging

The Giants left well enough alone because Kent was an essential cog in their lineup, the story died down and he missed only the first four regular-season games.

From Los Angeles Times ● Jul. 31, 2026

The enormous cash injection comes as Asia's fourth-largest economy rides high on a global AI boom -- with South Korean memory chipmakers emerging as a crucial cog in the fast-moving industry.

From Barron's ● Jun. 29, 2026

The town has felt the risk, if not the benefits, of being a cog in France’s military industry.

From The Wall Street Journal ● Jun. 14, 2026

Following Baggio at three is Ruud Gullit, a transformative cog in Silvio Berlusconi's own all-star cast assembled at San Siro after joining AC Milan from PSV for £6m in 1987.

From BBC ● Apr. 21, 2026

The big cog stayed well out from them, tacking.

From "A Clash of Kings" by George R.R. Martin

O. Fr. flosche, down: or from some Teut. word cog. with fleece—cf.

From Chambers's Twentieth Century Dictionary (part 2 of 4: E-M) by Various

BRAGI, the name of the God of Poetry; from braga, to glisten, to shine, or from bragga, to adorn; ph. cog. with G. pracht, splendour.

From The Elder Eddas of Saemund Sigfusson; and the Younger Eddas of Snorre Sturleson by Saemund Sigfusson

"Professor McCabe and Rajah will stay here for a day or two, strictly in cog., you know."

From Shorty McCabe by F. Vaux (Francis Vaux) Wilson

L. anderius, andena; further ety. dubious, perhaps ultimately cog. with End.

From Chambers's Twentieth Century Dictionary (part 1 of 4: A-D) by Various

Yes, that in cog. business wasn't so worse, at fifty per.

From Shorty McCabe by F. Vaux (Francis Vaux) Wilson

The battery operated Space Express has cogged wheels and can travel vertically up or upside down on a cogged track.

From Nature ● Dec. 17, 2018

And then there's the marvellous Druzhba sanatorium by the sea at Yalta, a stack of cogged carousels rising out of a bank of trees, each notch a living space.

From The Guardian ● Feb. 7, 2011

A cogged contrivance in machinery by which a rotatory motion is converted into a reciprocating motion.

From The Sailor's Word-Book An Alphabetical Digest of Nautical Terms, including Some More Especially Military and Scientific, but Useful to Seamen; as well as Archaisms of Early Voyagers, etc. by Sir Edward Belcher

But the Trade Unions were another matter, and never a billet-creating measure came before Parliament but he strove vehemently to have its wheels cogged in with those of the existing Trade Union machine.

From A Crooked Mile by Oliver [pseud.] Onions

I would ye would reconcile it to your conscience so to act to him as I would have you, for his injustice to the poor and for his cogged oaths.

From Privy Seal His Last Venture by Ford Madox Ford

A new coreless direct drive motor should eliminate the minor cogging issue some SL-1200 turntables experienced — tiny vibrations that can cause rotation irregularities.

From The Verge ● Jan. 7, 2019

That is cogging that you ask of me.

From The Fifth Queen Crowned by Ford Madox Ford

I haue matter in my head against you and your cogging companions, Pistoll and Nym.

From The Merry Wives of Windsor The Works of William Shakespeare [Cambridge Edition] [9 vols.] by John Glover

For at least seventy out of his eighty years of life he had been cheating, cogging, betraying, and doing the Devil's service upon earth; and who shall say that his end was undeserved?

From The Strange Adventures of Captain Dangerous, Vol. 2 Who was a sailor, a soldier, a merchant, a spy, a slave among the moors... by George Augustus Sala

"This must be some idle notion, Catharine, or some trick of those cogging priests and nuns; it accords not with thy late cheerful willingness to wed Henry Smith."

From The Fair Maid of Perth Or, St. Valentine's Day by Sir Walter Scott

Related Words

• prong