a gear tooth, formerly especially one of hardwood or metal, fitted into a slot in a gearwheel of less durable material.
a cogwheel.
a person who plays a minor part in a large organization, activity, etc..
He's just a small cog in the financial department.
Carpentry. (in a cogged joint) the tongue in one timber, fitting into a corresponding slot in another.
Mining. a cluster of timber supports for a roof.
any of the teeth or projections on the rim of a gearwheel or sprocket
a gearwheel, esp a small one
a person or thing playing a small part in a large organization or process
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. ))
First recorded in 1525–35; origin uncertain
1855–60; special use of cog 1; replacing cock in same sense, special use of cock 1 (in sense of projection); see coak
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.
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Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
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
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
Her look evolves from a worn-out cog to a biker-like granny who’d seem natural riding on the back of Dennis Hopper’s hog.
From Los Angeles Times ● Apr. 3, 2026
Among the targets in recent days was the IRGC’s Tharallah headquarters on Sunday, a central cog in the forces’ protest-suppression machine.
From The Wall Street Journal ● Mar. 4, 2026
The cog was drifting on a sea of dragonglass beneath a bowl of stars, but all around the storm raged on.
From "A Dance with Dragons" by George R. R. Martin
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
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
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
"Professor McCabe and Rajah will stay here for a day or two, strictly in cog., you know."
From Shorty McCabe by Wilson, F. Vaux (Francis Vaux)
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
Round the loaf there were indentations, like a cogged wheel, such as the millwright made.
From Bevis The Story of a Boy by Jefferies, Richard
Butter is made in one of their pots with a churning-stick, consisting of a cogged wheel fixed on to the end of a wooden rod.
From The Tribes and Castes of the Central Provinces of India Volume II by Russell, R. V. (Robert Vane)
The teeth of the cogged wheel are usually made the thickest, so as to somewhat equalise the strength of the teeth on the two wheels.
From Modern Machine-Shop Practice, Volumes I and II by Rose, Joshua
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
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 Glover, John, librarian of Trinity College, Cambridge
I wonder if Santiago of Bressure be one of these cogging shirks.
From Gargantua and Pantagruel, Illustrated, Book 3 by Motteux, Peter Anthony
That is cogging that you ask of me.
From The Fifth Queen Crowned by Ford, Ford Madox
The spirit of the cogging dicers of Whitefriars took possession of the grave Senators of the City, Wardens of Trades, Deputies, Aldermen.
From The History of England, from the Accession of James II — Volume 4 by Macaulay, Thomas Babington Macaulay, Baron
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
