Plain English Meaning
The shaped parts of the airplane that air flows over to produce lift or control — the wings, the tail surfaces, and the propeller blades.
Full Definition
The shaped surfaces of an aircraft that are designed to produce aerodynamic forces when air flows over them — primarily the wings, horizontal stabilizer, vertical stabilizer, and propeller blades. Each of these surfaces has a curved cross-sectional shape (an airfoil) that generates lift, control authority, or thrust as air moves across it.
Context Anchor
You will see this term in discussions of ice protection on wings, tail surfaces, and other shaped aircraft surfaces exposed to .