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The act of undulating; a waving motion or vibration; as, the undulations of a fluid, of water, or of air; the undulations of sound.

One who advocates the undulatory theory of light. Whewell.

. -- Contour of ground (Surv.), the outline of the surface of ground with respect to its undulation, etc. -- Contour line (Topographical Suv.), the line in which a horizontal plane intersects a portion of ground, or the corresponding line in a map or chart.

To fold or plait in regular undulation in such a way that the material will retain the shape intended; to give a wavy apperance to; as, to crimp the border of a cap; to crimp a ruffle. Cf. Crisp. The comely hostess in a crimped cap. W. Irving.

To raise in waves or undulations; to ripple. Seas would be pools without the brushing air To curl the waves. Dryden.

showing undulation or fluctuation; as, a fluctuant tumor.

The motion or undulation of a fluid collected in a natural or artifical cavity, which is felt when it is subjected to pressure or percussion. Dunglison.

To move with quick vibrations or undulations; as, a sail flutters in the wind; a fluttering fan.

Ground swell. (a) (Bot.) The plant groundsel. [Obs.] Holland. (b) A broad, deep swell or undulation of the ocean, caused by a long continued gale, and felt even at a remote distance after the gale has ceased. -- Ground table. (Arch.) See Earth table, under Earth. -- Ground tackle (Naut.), the tackle necessary to sec…

he plate vibrates under the influence of a sound, the stylus makes minute indentations or undulations in the soft material, and these, when the cylinder or disk is again turned, set the plate in vibration, and reproduce the sound.

To rise in circles, ripples, or undulations; to curl; to mantle. thin winding breath which purled up to the sky. Shak.

The elevations and surface undulations of a country. Guyot. Relief valve, a valve arranged for relieving pressure of steam, gas, or liquid; an escape valve.

as water when agitated or running over a rough bottom; to be covered with small waves or undulations, as a field of grain.

Having gradual, rounded undulations of surface; as, a rolling country; rolling land. [U.S.] Rolling bridge. See the Note under Drawbridge. -- Rolling circle of a paddle wheel, the circle described by the point whose velocity equals the velocity of the ship. J. Bourne. -- Rolling fire (Mil.), a discharge of firearms b…

An ornament formed of undulations giving off spirals or sprays, usually suggestive of plant form. Roman architectural ornament is largely of some scroll pattern.

ograph which sits in the groove of a phonograph record while it is turning, to detect the undulations in the phonograph groove and convert them into vibrations which are transmitted to a system (since 1920 electronic) which converts the signal into sound; also called needle. The stylus is frequently composed of metal o…

Anything drawn behind in long undulations; a train. "A radiant trail of hair." Pope.

To cause to move backward and forward, or up and down, in undulations or waves; to cause to vibrate. Breath vocalized, that is, vibrated and undulated. Holder.

Consisting in, or accompanied by, undulations; undulatory.

Moving in the manner of undulations, or waves; resembling the motion of waves, which successively rise or swell rise or swell and fall; pertaining to a propagated alternating motion, similar to that of waves. Undulatory theory, or Wave theory (of light) (Opt.), that theory which regards its various phenomena as due to…