The Collaborative International Dictionary of English v.0.48:

Volatileness \Vol"a*tile*ness\, Volatility \Vol`a*til"i*ty\, n.
   [Cf. F. volatilit['e].]
   Quality or state of being volatile; disposition to evaporate;
   changeableness; fickleness.
   [1913 Webster]

   Syn: See Levity.
        [1913 Webster]

WordNet (r) 3.0 (2006):

volatility
    n 1: the property of changing readily from a solid or liquid to
         a vapor
    2: the trait of being unpredictably irresolute; "the volatility
       of the market drove many investors away" [syn: volatility,
       unpredictability]
    3: being easily excited [syn: excitability, excitableness,
       volatility]

Moby Thesaurus II by Grady Ward, 1.0:

79 Moby Thesaurus words for "volatility":
   airiness, animation, ascent, brainlessness, bubbliness, buoyancy,
   caducity, changeability, changeableness, coquettishness,
   corruptibility, daintiness, death, delicacy, downiness,
   empty-headedness, ephemerality, ephemeralness, ethereality,
   evanescence, evaporability, faddishness, faddism, fickleness,
   finitude, fleetingness, flightiness, flippancy, floatability,
   fluffiness, foaminess, foolishness, frivolity, frivolousness,
   frothiness, fugacity, gentleness, giddiness, gossameriness,
   impermanence, impermanency, inconstancy, instability,
   lack of depth, lack of weight, levitation, levity, lightness,
   mercuriality, mercurialness, momentariness, mortality, mutability,
   perishability, shallow-wittedness, shallowness, skittishness,
   softness, sprightliness, superficiality, tenderness, thinness,
   thoughtlessness, transience, transiency, transientness,
   transitoriness, undependability, unheaviness, unpredictability,
   unprofoundness, unprofundity, unreliability, vaporability,
   vaporizability, variability, weightlessness, witlessness,
   yeastiness