Ornithopter (or Orthopter)—A flapping wing design of aircraft intended to imitate the flight of a bird.

Outrigger—This term is usually applied to the framework connecting the main surface with an elevator placed in advance of it. Sometimes applied to the "tail-boom" framework connecting the tail-plane with the main lifting surface. [20]

Pancake, to—To "stall."

Plane—This term is often applied to a lifting surface. Such application is not quite correct, since "plane" indicates a flat surface, and the lifting surfaces are always cambered.

Propeller—See "Air-Screw."

Propeller, Tractor—An air-screw mounted in front of the main lifting surface.

Propeller, Pusher—An air-screw mounted behind the main lifting surface.

Pusher—An aeroplane of which the propeller is mounted behind the main lifting surface.

Pylon—Any V-shaped construction from the point of which wires are taken.

Power—Rate of working. [21]