cog

UK: /ˈkɒg/ US: /kɑg, kɔg/ ,(kog, kôg)

Inflections of 'cog' (v): (⇒ conjugate)

cogs

v 3rd person singular

cogging

v pres p

cogged

v past

cogged

v past p

WordReference Random House Learner's Dictionary of American English © 2025

cog¹ /kɑg, kɔg/   n. [countable]

1. Mechanical Engineering a gear tooth that fits into the slot on a wheel with similar teeth, to transfer motion or power
2. Mechanical Engineering a cogwheel.
3. a person who plays a minor part in an organization, etc.:
   He's just a small cog in this business.

WordReference Random House Unabridged Dictionary of American English © 2025

cog¹  (kog, kôg), n., v., cogged, cog•ging. 
n. 

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

v.i. 

4. Electricity (of an electric motor) to move jerkily.

v.t. 

5. Metallurgy to roll or hammer (an ingot) into a bloom or slab.
6. Idioms slip a cog, to make a blunder;
   err:
   One of the clerks must have slipped a cog.

• Scandinavian; compare Swedish, Norwegian kugg cog
• Middle English cogge, probably 1200–50

cog²  (kog, kôg), v., cogged, cog•ging. 
v.t. 

1. Games to manipulate or load (dice) unfairly.

v.i. 

2. Games to cheat, esp. at dice.

• origin, originally uncertain 1525–35

cog³  (kog, kôg), n., v., cogged, cog•ging. 
n. 

1. Building [Carpentry.] (in a cogged joint) the tongue in one timber, fitting into a corresponding slot in another.
2. Mining, Building a cluster of timber supports for a roof. Cf. chock (def. 4).

v.t., v.i. 

3. Building [Carpentry.] to join with a cog.

• 1855–60; special use of cog¹; replacing cock in same sense, special use of cock¹ (in sense of projection); see coak

cog., 

1. Linguistics cognate.

Collins Concise English Dictionary © HarperCollins Publishers::

cog / 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

Etymology: 13th Century: of Scandinavian origin; compare Danish kogge, Swedish kugge, Norwegian kug

cog / kɒɡ/ noun

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

verb (cogs, cogging, cogged)

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

Etymology: 19th Century: of uncertain origin