Railroad Dictionary

Yard	A system of tracks other than main tracks and sidings. A yard is used for making up trains, for storing cars, and for other purposes.
Yard Clerk	Person engaged in clerical work in and around yards and terminals. In some locations, person engaged in checking tracks.
Yard Engine	An engine being used in yard service.
Yard Foreman	A yard conductor.
Yard Limits	A portion of main track designated by special instructions. Yard limits are identified by signs.
Yard Office	Building erected within a yard or terminal in which business is conducted.
Yard Slug	A cabless slug unit, not equipped with a diesel engine, but equipped with MU capability and traction motors, which receive electrical power from a mother locomotive.
Yardmaster	Person responsible for control of trains and engines operating within a yard.