Real Dictionary

cog
countable noun: A cog is a wheel with square or triangular teeth around the edge, which is used in a machine to turn another wheel or part.

cog in American English 1
any of a series of teeth on the rim of a wheel, for transmitting or receiving motion by fitting between the teeth of another wheel; gear tooth
noun: a gear tooth, formerly esp. one of hardwood or metal, fitted into a slot in a gearwheel of less durable material

cog in American English 2
a projection on a beam that fits into a corresponding groove or notch in another beam, making a joint
to join by a cog or cogs
intransitive verb: to cheat, esp. at dice
transitive verb: to manipulate or load (dice) unfairly

cog in American English 3
a deception; trick
to cheat; swindle
to manipulate (dice) in a fraudulent manner
noun: the tongue in one timber, fitting into a corresponding slot in another

cog in American English 4
cognate

cog in British English 1
noun: any of the teeth or projections on the rim of a gearwheel or sprocket
verb: to roll (cast-steel ingots) to convert them into blooms

cog in British English 2
verb: to cheat (in a game, esp dice), as by loading a dice

cog in British English 3
noun: a tenon that projects from the end of a timber beam for fitting into a mortise
verb: to join (pieces of wood) with cogs

cog in Mechanical Engineering
noun: A cog is a tooth at the edge of a gear wheel or sprocket.

cog. in American English
abbreviation: cognate