[ kog, kawg ]
/ kɒg, kɔg /


(not in technical use) a gear tooth, formerly especially one of hardwood or metal, fitted into a slot in a gearwheel of less durable material.
a person who plays a minor part in a large organization, activity, etc.: He's just a small cog in the financial department.

verb (used without object), cogged, cog·ging.

(of an electric motor) to move jerkily.

verb (used with object), cogged, cog·ging.

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



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Idioms for cog

    slip a cog, to make a blunder; err: One of the clerks must have slipped a cog.

Origin of cog

1200–50; Middle English cogge, probably < Scandinavian; compare Swedish, Norwegian kugg cog Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

British Dictionary definitions for slip a cog (1 of 3)

/ (kɒɡ) /


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

verb cogs, cogging or cogged

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

Word Origin for cog

C13: of Scandinavian origin; compare Danish kogge, Swedish kugge, Norwegian kug

British Dictionary definitions for slip a cog (2 of 3)

/ (kɒɡ) /

verb cogs, cogging or cogged

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

Word Origin for cog

C16: originally a dice-playing term, of unknown origin

British Dictionary definitions for slip a cog (3 of 3)

/ (kɒɡ) /


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

verb cogs, cogging or cogged

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

Word Origin for cog

C19: of uncertain origin
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Idioms and Phrases with slip a cog (1 of 2)

slip a cog

Also, slip a gear or one's gears. Lose one's ability to reason soundly or make correct judgments, as in She must have slipped a cog or she would never have gone out barefoot in December, or What's the matter with him? Has he slipped his gears? These slangy usages allude to a mechanical failure owing to the cog of a gear or a gear failing to mesh. The first dates from about 1930, the variant from the 1960s.

Idioms and Phrases with slip a cog (2 of 2)


The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.