Biplane

Bi"plane, n. [Pref. bi- + plane.] (Aëronautics)

Defn: An aëroplane with two main supporting surfaces one above the other.

Bi"plane, a. (Aëronautics)

Defn: Having, or consisting of, two superposed planes, aërocurves, or the like; of or pertaining to a biplane; as, a biplane rudder.