The Collaborative International Dictionary of English v.0.48:

Dissipation \Dis`si*pa"tion\ (d[i^]s`s[i^]*p[=a]"sh[u^]n), n.
   [L. dissipatio: cf. F. dissipation.]
   1. The act of dissipating or dispersing; a state of
      dispersion or separation; dispersion; waste.
      [1913 Webster]

            Without loss or dissipation of the matter. --Bacon.
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            The famous dissipation of mankind.    --Sir M. Hale.
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   2. A dissolute course of life, in which health, money, etc.,
      are squandered in pursuit of pleasure; profuseness in
      vicious indulgence, as late hours, riotous living, etc.;
      dissoluteness.
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            To reclaim the spendthrift from his dissipation and
            extravagance.                         --P. Henry.
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   3. A trifle which wastes time or distracts attention.
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            Prevented from finishing them [the letters] a
            thousand avocations and dissipations. --Swift.
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   Dissipation of energy. Same as Degradation of energy,
      under Degradation.
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WordNet (r) 3.0 (2006):

dissipation
    n 1: breaking up and scattering by dispersion; "the dissipation
         of the mist"
    2: dissolute indulgence in sensual pleasure [syn: profligacy,
       dissipation, dissolution, licentiousness, looseness]
    3: useless or profitless activity; using or expending or
       consuming thoughtlessly or carelessly; "if the effort brings
       no compensating gain it is a waste"; "mindless dissipation of
       natural resources" [syn: waste, wastefulness,
       dissipation]

Moby Thesaurus II by Grady Ward, 1.0:

140 Moby Thesaurus words for "dissipation":
   abandon, abandonment, ablation, amusement, attenuation, attrition,
   blackout, blocking, broadcast, broadcasting, carousal, carouse,
   carpe diem, circumfusion, conspicuous consumption, consumption,
   corrosion, debauch, debauchery, debauchment, decrease, decrement,
   deliquescence, dematerialization, departure, depletion,
   depreciation, diffraction, diffusion, dilution, disappearance,
   disappearing, dispensation, dispersal, dispersion, dissemination,
   dissoluteness, dissolution, dissolving, distraction, distribution,
   divergence, diversion, divertissement, drain, eclipse, elimination,
   entertainment, erasure, erosion, evanescence, evaporation,
   exhaustion, expansion, expenditure, extinction, extravagance,
   fadeaway, fadeout, fading, fastness, fragmentation, free living,
   gallantry, going, hedonism, high living, impoverishment,
   incontinence, intemperance, killing pace, lavishness, leakage,
   leaking purse, libertinage, libertinism, license, licentiousness,
   loose purse strings, loss, melting, occultation, orgy,
   overgenerosity, overgenerousness, overindulgence, overliberality,
   passing, peppering, pound-foolishness, prodigality, profligacy,
   profuseness, profusion, propagation, publication, radiation,
   rakishness, reckless expenditure, reckless spending, recklessness,
   recreation, riotous living, saturnalia, scattering, scatterment,
   self-gratification, self-indulgence, sensualism, shotgun pattern,
   shrinkage, sowing, spattering, splay, spread, spreading,
   sprinkling, squandering, squandermania, strewing, sybaritism,
   unbridledness, using, using up, vanishing, vanishing point, venery,
   volatilization, voluptuousness, wantonness, wastage, waste,
   wastefulness, wear and tear, wearing, wearing away, wenching,
   whoring, wildness, wipe