Train

b) a locomotive not coupled to any other rolling stock.
• United States
In the United States, the term consist is used to describe the group of rail vehicles which make up a train. When referring to motive power, consist refers to the group of locomotives powering the train. Similarly, the term trainset refers to a group of rolling stock that is permanently or semi-permanently coupled together to form a unified set of equipment (the term is most often applied to passenger train configurations).
The Atchison, Topeka and Santa Fe Railway's 1948 operating rules define a train as: "An engine or more than one engine coupled, with or without cars, displaying markers."