Fluctuation - crowlogic/arb4j GitHub Wiki

The term "excitation" is an excellent alternative word to describe incoming fluctuations of a (stochastic) system because it carries a neutral connotation and refers to the process of a system being impinged upon by something external to it which moves it from its equilibrium state and represents the random fluctuating variations that affect the system.

So, the incoming fluctuations of a stochastic system will be dubbed "incoming excitations", highlighting the dynamic nature of the system without the negative connotation associated with the historical term "perturbation."

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  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]

From WordNet (r) 3.0 (2006) [wn]:

  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}]

From Moby Thesaurus II by Grady Ward, 1.0 [moby-thesaurus]:

  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