Chassis and Underframe

Chassis noun - The skeleton of a motor vehicle consisting of a steel frame supported on springs that holds the body and motor.

Underframe and chassis are semantically related in undercarriage topic. In some cases you can use "Underframe" instead a noun "Chassis".

Underframe noun - The internal supporting structure that gives an artifact its shape.

Chassis and underframe are semantically related in undercarriage topic. You can use "Chassis" instead a noun "Underframe".