Plain English Meaning
The physical body and structure of the aircraft itself — everything that holds it together and gives it shape — not counting the engine or the electronic equipment.
Full Definition
The structural components of an aircraft, including the fuselage, wings, empennage (tail section), landing gear, and associated control surfaces, but excluding the powerplant (engine) and avionics.
Context Anchor
Seen in FAA certification, maintenance, and inspection discussions, especially when distinguishing airframe work from engine work.