Sesquiplane is a rare technical term that refers to an aircraft with one and a half times the length of the upper wing as compared to the lower wing. However, there are some synonyms available for this term such as- biplane, monoplane, triplane, quadruplane and multiplane. These words possess their own different meanings and types of aircraft. The biplane has two wings one placed below the other, while the monoplane has a single pair of wings attached to the fuselage. The triplane has three sets of wings and quadruplane has four pairs of wings. Similarly, a multiplane can have more than four pairs of wings and used for experimental purposes. In summary, while Sesquiplane may not have many synonyms, there are a wide range of synonyms for various types of aircraft.