I. ˈbī+ˌ- noun
Etymology: bi- (I) + plane
: an airplane with two main supporting surfaces usually placed one above the other
II. adjective
Etymology: bi- (I) + plane
: acting in or taking place from two planes
a biplane examination of the hip joint
biplane fluoroscopy
: having parts arranged in two planes especially at right angles to one another
a biplane filament lamp