An auto is an automobile, car, or motorcar designed for the primary purpose of transporting people. The word “automobile” is derived from the ancient Greek word “autos,” meaning self, and “mobile,” the French derivative of the Latin word “mobilis,” meaning movable.
The U.S. government’s definition of “automobile” starts like this:
“An automobile is any 4-wheeled vehicle that is propelled by fuel, or by alternative fuel, manufactured primarily for use on public streets, roads, and highways and rated at less than 10,000 pounds gross vehicle weight.”
As government definitions often do, it lists exceptions like “operated only on a rail line.”
An auto may also refer to an automatic transmission, part of a car’s drivetrain. The transmission connects the engine and the wheels, applying drive ratios to manage power and make the car move. A manual transmission requires the driver to operate a clutch and gear selector to engage the right gear for conditions. An automatic transmission, or auto, changes gears while the car is in motion without the driver’s direct intervention.
