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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

And for these Dodgers — whose fourth starter, Tyler Glasnow, was a key cog in last year’s World Series-winning rotation — it’s a fair assessment.

From Los Angeles Times ● Oct. 4, 2026

Muse is another major cog in the return-on-investment engine.

From The Wall Street Journal ● Sep. 18, 2026

When mediocrity is the core objective of an extremely powerful company like this one, success hinges on turning the once-discerning viewer into a machine cog as mindless as one of Netflix’s baffling originals.

From Salon ● Sep. 2, 2026

"At a men's game, you feel like you're just a cog," says Donna Jones, a season ticket-holder at London City Lionesses.

From BBC ● Jul. 24, 2026

We were a cog in a machine that would get the forged documents to Jewish people whose lives depended on receiving them.

From "Code Name Kingfisher" by Liz Kessler

"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

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

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

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

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

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

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

It consists of a wooden frame containing cogged iron wheels of increasing powers.

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

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

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

But here goes at you: "Ye cogging Greeks, have at ye both."

From The Tribune of Nova Scotia A Chronicle of Joseph Howe by W. L. (William Lawson) Grant

Those principally used are the following: lap, fished, scarf, notching, cogging, dovetailing, housing, halving, mortice and tenon, stub 387 tenon, dovetailed tenon, tusk tenon, joggle, bridle, foxtail wedging, mitre, birdsmouth, built-up, dowel.

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

That is cogging that you ask of me.

From The Fifth Queen Crowned by Ford Madox Ford

Related Words

• prong