Ŭn'du-lā'tion, n.

n. [N. Lat. undulatio, It. undulazione, ondulazione, Sp. undulacion, ondulacion, Fr. ondulation.]

1. A waving motion or vibration; as, the undulations of a fluid, of water, or air; the undulations of sound.
2. (Med.) The movement of a fluid collected in any natural or artificial cavity, which is felt by pressure or by percussion, properly practiced; — called also fluctuation. Dunglison.
3. (Mus.) A rattling or jarring of sounds, as when discordant tones are sounded together; — called also beat.
4. (Physics.) A motion to and fro, up and down, or from side to side, in any fluid medium, propagated continuously among its particles, involving sometimes alternate compression and dilatation, but with no translation of the particles themselves corresponding to the propagation of the wave; a wave-motion; a vibration.