noun. 1 a flat or level surface. 2 a surface generated by a straight line moving at a constant velocity with respect to a fixed point. 3 a level of dignity, character, existence, development, or the like. 4 a thin extended section affording a supporting surface.

verb. 1 to glide or soar. 2 to rise partly out of the water when moving at high speed. 3 to fly or travel in an airplane. origin. latin planum ‘flat surface’, from planus ‘plain’