- a wave.
- the motion of waves.
Examples from the Web for undulation
Growth stretches for miles, without ever a hint of undulation.The Personality of American Cities|Edward Hungerford
The sea has three kinds of motion: the first is that undulation which is occasioned by the wind.The Mosaic History of the Creation of the World|Thomas Wood
And of undulation itself, there are all manner of visible conditions, which are not true conditions.The Storm-Cloud of the Nineteenth Century|John Ruskin
It had no fins that I could perceive, and seemed to me to move progressively by undulation up and down.Mythical Monsters|Charles Gould
The undulation of the waves after a gale; long hollow-jawed sea; ground-swell.The Sailor's Word-Book|William Henry Smyth