fluctuate

American Heritage® Dictionary of the English Language, Fourth Edition

1. v. To vary irregularly. See Synonyms at swing.
2. v. To rise and fall in or as if in waves; undulate.
3. v. To cause to rise and fall or vary irregularly.

Century Dictionary and Cyclopedia

1. To have a wave-like motion; rise and fall in level or degree; undulate; waver.
2. To move or pass backward and forward as if on waves; be wavering or unsteady; rise and fall; change about: as, public opinion often fluctuates; the funds or the prices of stocks fluctuate.
3. Synonyms Fluctuate, Vacillate, Waver, Oscillate, Undulate, apply to literal or figurative movements to and fro, or up and down; but undulate is used only physically, as of the sea, sound-waves, etc. Fluctuate, waver, and undulate in their figurative uses are founded upon the rise and fall of waves; oscillate refers to the swinging of a pendulum. Vacillate, and next to it waver, suggests the most of mental or moral indecision. Oscillate naturally suggests the most regular alternations of movement to and fro. Vacillate and waver are now rarely used of physical things; waver is also used of a hesitation that seems likely to end in yielding.
4. To put into a state of fluctuating or wave-like motion.
5. To cause to waver or be undecided.

Wiktionary

1. v. intransitive To vary irregularly; to swing.
2. v. intransitive To undulate.
3. v. transitive To cause to vary irregularly.

GNU Webster's 1913

1. v. To move as a wave; to roll hither and thither; to wave; to float backward and forward, as on waves.
2. v. To move now in one direction and now in another; to be wavering or unsteady; to be irresolute or undetermined; to vacillate.
3. v. rare To cause to move as a wave; to put in motion.

WordNet 3.0

1. v. cause to fluctuate or move in a wavelike pattern
2. v. be unstable
3. v. move or sway in a rising and falling or wavelike pattern