To move freely back and forth or up and down in the air, as branches in the wind, To cause to move back and forth or up and down, either once or repeatedly, To arrange into curves, curls, or undulations, noun_ One of a series of curves in a waving line, or of ridges in a furrowed surface; an undulation; a swell, A disturbance that travels through a medium. Energy is transferred by a wave from one region of the medium to another without causing any permanent displacement of the medium, A moving curve or succession of curves in or on a surface; an undulatio