Source : Webster's Revised Unabridged Dictionary (1913)

Oscillate \Os"cil*late\, v. i. [imp. & p. p. {Oscillated}; p.
   pr. & vb. n. {Oscillating}.] [L. oscillare to swing, fr.
   oscillum a swing, a little mask or puppet made to be hung
   from trees and swing in the wind, prob. orig., a little
   mouth, a dim. from os mouth. See {Oral}, and cf. {Osculate}.]
   1. To move backward and forward; to vibrate like a pendulum;
      to swing; to sway.

   2. To vary or fluctuate between fixed limits; to act or move
      in a fickle or fluctuating manner; to change repeatedly,
      back and forth.

            The amount of superior families oscillates rather
            than changes, that is, it fluctuates within fixed
            limits.                               --Dc Quincey.