—v.i. 1. to move with a sinuous or wavelike motion; display a smooth rising-and-falling or side-to-side alternation of movement: The flag undulates in the breeze. 2. to have a wavy form or surface; bend with successive curves in alternate directions.
3. (of a sound) to rise and fall in pitch: the wail of a siren undulating in the distance.
—v.t. 1. to cause to move in waves.
2. to give a wavy form to.
—adj. Also,un'du•lat"ed.having a wavelike or rippled form, surface, edge, etc.; wavy.