(from the article `biplane`) ...and shock waves would interact to reduce drag (the `shape drag` due to the thickness of the airfoil sections). A biplane having one much smaller ...
sesquiplane A fixed-wing aircraft (biplane) with one pair of wings much longer than the other pair.
An aeroplane with two wings (or pairs of wings), where one (often the lower) is significantly smaller than the other in span and/or chord.
A biplane with a much smaller bottom plane, sometimes called a one-and-a-half plane.