undulation

noun

1. an act of undulating; a wavelike motion.
2. a wavy form or outline.
3. one of a series of wavelike bends, curves, or elevations.
4. Physics.
   1. a wave.
   2. the motion of waves.

noun

1. the act or an instance of undulating
2. any wave or wavelike form, line, etc

n.1640s, from Medieval Latin *undulatio, from Late Latin undulatus “wavy, undulated,” from undula “wavelet,” diminutive of Latin unda “wave” (see water).