biplanes is a form of:

Biplane



noun
1.
(an aircraft or glider with two sets of wings) យន្ដហោះស្លាបពីរជាន់
ENGLISH MEANING
noun
1.
An aeroplane with two main supporting surfaces one above the other.
adjective
1.
Having, or consisting of, two superposed planes, aerocurves, or the like; of or pertaining to a biplane; as, a biplane rudder.