The Collaborative International Dictionary of English v.0.48:

Fluctuation \Fluc`tu*a"tion\, n. [L. fluctuatio; cf. F.
   fluctuation.]
   1. A motion like that of waves; a moving in this and that
      direction; as, the fluctuations of the sea.
      [1913 Webster]

   2. A wavering; unsteadiness; as, fluctuations of opinion;
      fluctuations of prices.
      [1913 Webster]

   3. (Med.) 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.
      [1913 Webster]

WordNet (r) 3.0 (2006):

fluctuation
    n 1: a wave motion; "the fluctuations of the sea"
    2: an instance of change; the rate or magnitude of change [syn:
       variation, fluctuation]
    3: the quality of being unsteady and subject to changes; "he
       kept a record of price fluctuations" [syn: fluctuation,
       wavering]

Moby Thesaurus II by Grady Ward, 1.0:

95 Moby Thesaurus words for "fluctuation":
   alternation, arrhythmia, asking price, bearish prices, bid price,
   book value, brokenness, bullish prices, call price, capriciousness,
   choppiness, closing price, decline, desultoriness,
   disconnectedness, discontinuity, eccentricity, equivocation,
   erraticness, face value, fibrillation, fitfulness, fits and starts,
   fixed price, flash price, flurry, flutter, frequency,
   frequency band, frequency spectrum, harmonic motion, high,
   inconstancy, intermittence, irregularity, issue par, issue price,
   jerkiness, libration, low, market price, market value,
   nominal value, nonuniformity, nutation, offering price,
   opening price, oscillation, par, par value, parity, patchiness,
   pendulation, periodicity, price, put price, quotation,
   quoted price, rally, resonance, resonance frequency, roughness,
   seesawing, settling price, shifting, shilly-shally,
   shilly-shallying, shuffling, spasticity, sporadicity, sporadicness,
   spottiness, stagger, stated value, swings, teeter-tottering,
   teetering, tottering, uncertainty, unevenness, unmethodicalness,
   unpredictability, unsteadiness, unsystematicness, vacillation,
   variability, variation, vibrancy, vibratility, vibration,
   vicissitude, wavering, whimsicality, wobble, wobbling