Motor Vehicle

Any mechanically or electrically powered device not operated on rails, upon which or by which any person or property may be transported upon a land highway. The load on a motor vehicle or trailer attached to it is considered part of the vehicle. (NSC1)

A vehicle, machine, tractor, trailer, or semitrailer, or any combination thereof, propelled or drawn by mechanical power and used upon the highways in the transportation of passengers or property. It does not include a vehicle, locomotive, or car operated exclusively on a rail or rails, or a trolley bus operated by electric power derived from a fixed overhead wire, furnishing local passenger transportation similar to street-railway service. (49CFR171) (49CFR383) (49CFR390) 

See also Automobile, Bus, Car, Minivan, Semitrailer, Taxi, Tractor (or Truck Tractor), Tractor-Semitrailer, Truck, Van, Vehicle.