3. (Mus.) (a) The tremulous tone produced by a peculiar pressure of the
finger on a string, as of a violin. (b) The pulsation caused by the
vibrating together of two tones not quite in unison; — called also
beat.
4. (Physics) A motion to and fro, up and down, or from side to side, in
any fluid or elastic medium, propagated continuously among its
particles, but with no translation of the particles themselves in the
direction of the propagation of the wave; a wave motion; a vibration.
Un`du*la"tion*ist, n. One who advocates the undulatory theory of light.
Whewell.
Un"du*la*tive (?), a. Consisting in, or accompanied by, undulations;
undulatory.
Un"du*la*to*ry (?; 277), a. [Cf. F. ondulatoire.] 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 undulations in an ethereal
medium, propagated from the radiant with immense, but measurable,
velocities, and producing different impressions on the retina according
to their amplitude and frequency, the sensation of brightness depending
on the former, that of color on the latter. The undulations are
supposed to take place, not in the direction of propagation, as in the
air waves constituting sound, but transversely, and the various
phenomena of refraction, polarization, interference, etc., are
attributable to the different affections of these undulations in
different circumstances of propagation. It is computed that the
frequency of the undulations corresponding to the several colors of the
spectrum ranges from 458 millions of millions per second for the
extreme red ray, to 727 millions of millions for the extreme violet,
and their lengths for the same colors, from the thirty-eight thousandth
to the sixty thousandth part of an inch. The theory of ethereal
undulations is applicable not only to the phenomena of light, but also
to those of heat.
Un*dull" (?), v. t. [1st pref. un- + dull.] To remove the dullness of;
to clear. [Obs.] Whitlock.
Un"du*lous (?), a. Undulating; undulatory.
Un*du"ly (?), adv. In an undue manner.
Un*dump"ish (?), v. t. [1st pref. un- + dumpish.] To relieve from the
dumps. [Obs.] Fuller.