An Etymological Dictionary of Astronomy and Astrophysics

A wave; the motion of waves.
A wavelike motion in any medium.

Etymology (EN): From L.L. undulatus “wavy, undulated,” from undula “wavelet,” diminutive of L. unda “wave.”

Etymology (PE): Mowješ, verbal noun of mowjidan “to undulate,” from mowj→ wave.