Motor vehicle definition clarifies GST scope for road vehicles, chassis, trailers and specified statutory exclusions under law. Motor vehicle for GST is defined by reference to the Motor Vehicles Act, 1988, encompassing any mechanically propelled vehicle adapted for road use, and explicitly including a chassis without a body and a trailer. Exclusions comprise vehicles on fixed rails, vehicles designed only for factory or enclosed-premises use, and small under-four-wheel vehicles with limited engine capacity. Statutory definitions separately describe a trailer as a vehicle drawn by a motor vehicle and a semi-trailer as a non-mechanically propelled vehicle constructed to bear part of its weight on the towing motor vehicle.