- the lower frame on which a vehicular structure rests: the underframe of a bus.
Origin of underframe
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for underframe
On this underframe the superstructure or frame is erected to form the body of the car.The Story of the Pullman Car
M, is of the internal pole type, and is supported on the underframe of the wagon.
The underframe is provided with spring axle boxes, and also with spring buffers and drawbars.