A chassis (plural: “chassis”) consists of a framework which supports an inanimate object.

In the case of a motor vehicle, the term chassis means the frame plus the “running gear” like engine, transmission, driveshaft, differential, and suspension. A body (sometimes referred to as “coachwork”), which is usually not necessary for integrity of the structure, is built on the chassis to complete the vehicle.

In an airplane the chassis consists only of the landing gear or undercarriage, not the airframe itself.