Amtrak unit refers to a train operated by Amtrak, the National Railroad Passenger Corporation in the United States. Some popular synonyms for this term include passenger cars, train sets, locomotives, and rolling stock. Passenger cars are the individual cars that make up a train, and train sets typically refer to a group of cars that are designed to be used together for a specific route or journey. Locomotives are the engines that pull the train and are responsible for its movement. Lastly, rolling stock is a general term used to describe any vehicle or equipment that moves on a railway track. Regardless of the term used, all Amtrak units are designed to provide safe and reliable transportation for passengers across the United States.