biplane /ˈbaɪpleɪn/adjective 2noun 1verb 1forms 3 adjective2 •Composed of, or relating to, two planes (flat surfaces extending infinitely in all directions). •Having, or consisting of, two superposed planes, aerocurves, etc. noun1 •An airplane that has two main wings, one above the other and supported by struts. verb1 •(rare) To fly in a biplane. formsbiplaned · biplaning · biplanes