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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

“I hated being a cog in a wheel, just moving things around.”

From Los Angeles Times ● Aug. 6, 2026

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

Take that away and the message is clear: You’re a cog.

From The Wall Street Journal ● Jun. 14, 2026

"You require passage for a hundred Dothraki, all their horses, yourself and this knight, and three dragons?" said the captain of the great cog Ardent Friend before he walked away laughing.

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

"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

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

VASADR, from vas, moisture, a word cog. with the E. wet and wash.

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

GRAFVITNIR, from the v. grafa, to dig, to delve; cog. with E. grave: and the v. vita, to know; to wit, wist, wot.

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

Prof. Professor. c., cent. century. mech. mechanics. pron. pronoun; carp. carpentry. med. medicine. pronounced; cf. compare. metaph. metaphysics. pronunciation. chem. chemistry. mil. military. prop. properly. cog. cognate.

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

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

The mitre wheel, working with other cogged wheels, communicates the motion of the direction shaft to a cylinder carrying a pencil, to record the direction.

From A Treatise on Meteorological Instruments Explanatory of Their Scientific Principles, Method of Construction, and Practical Utility by Henry Negretti

“Why, I forgot them,” he said, taking from where they lay a couple of small cogged wheels which he had cleaned very carefully, and put on one side early in his task.

From The Weathercock Being the Adventures of a Boy with a Bias by A.W. Cooper

It was about a month after this that I began to find myself pitted against Miss Dean in a struggle for some dimly grasped advantage, with the dice cogged against me.

From A Woman of Genius by Mary Hunter Austin

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

Such a system of cogging, such a system of fraud, such a system of prevarication, such a system of falsehood, never was, I believe, before exhibited in the world.

From The Works of the Right Honourable Edmund Burke, Vol. 10 (of 12) by Edmund Burke

The hammered billets are again slowly heated and receive a second hammering, known as "cogging."

From The Working of Steel Annealing, Heat Treating and Hardening of Carbon and Alloy Steel by Fred H. (Fred Herbert) Colvin

If the Venetian boxes be the most sovereign of all remedies against this same cogging, is it not a strange thing that they should be thrown first into the fire by a fair gamester?

From The Commonwealth of Oceana by James Harrington

The carpenter frames or combines separate pieces of timber by scarfing, notching, cogging, tenoning, pinning and wedging, &c.

From Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 4 "Carnegie Andrew" to "Casus Belli" by Various

Related Words

• prong