An aeroplane with three sets of wings, one above the other.

An aeroplane with three similar-sized wings (or pairs of wings), exactly or approximately in vertical alignment.

A triplane is a fixed-wing aircraft equipped with three sets of wings, each roughly the same size and mounted one above the other. Typically, the lower set of wings would be level with the underside of the aircraft's fuselage, the middle set level with the top of the fuselage, and the top set supported above the fuselage on struts. The first triplane was designed in 1908 by Ambroise Goupy and built by Blériot, flown with a 37 kW (50 hp) Renault engine.