Source : Webster's Revised Unabridged Dictionary (1913)

Dissipate \Dis"si*pate\, v. i.
   1. To separate into parts and disappear; to waste away; to
      scatter; to disperse; to vanish; as, a fog or cloud
      gradually dissipates before the rays or heat of the sun;
      the heat of a body dissipates.

   2. To be extravagant, wasteful, or dissolute in the pursuit
      of pleasure; to engage in dissipation.

Dissipate \Dis"si*pate\, v. t. [imp. & p. p. {Dissipated}; p.
   pr. & vb. n. {Dissipating}.] [L. dissipatus, p. p. of
   dissipare; dis- + an obsolete verb sipare, supare. to throw.]
   1. To scatter completely; to disperse and cause to disappear;
      -- used esp. of the dispersion of things that can never
      again be collected or restored.

            Dissipated those foggy mists of error. --Selden.

            I soon dissipated his fears.          --Cook.

            The extreme tendency of civilization is to dissipate
            all intellectual energy.              --Hazlitt.

   2. To destroy by wasteful extravagance or lavish use; to
      squander.

            The vast wealth . . . was in three years dissipated.
                                                  --Bp. Burnet.

   Syn: To disperse; scatter; dispel; spend; squander; waste;
        consume; lavish.

Source : WordNet®

dissipate
     v 1: to cause to separate and go in different directions; "She
          waved her hand and scattered the crowds" [syn: {disperse},
           {dispel}, {break up}, {scatter}]
     2: move away from each other; "The crowds dispersed"; "The
        children scattered in all directions when the teacher
        approached"; [syn: {disperse}, {scatter}, {spread out}]
     3: spend frivolously and unwisely; "Fritter away one's
        inheritance" [syn: {fritter}, {frivol away}, {shoot}, {fritter
        away}, {fool}, {fool away}]
     4: live a life or pleasure, especially with respect to
        alcoholic consumption