Source : Webster's Revised Unabridged Dictionary (1913)

Dissociate \Dis*so"ci*ate\, v. t. [imp. & p. p. {Dissociated};
   p. pr. & vb. n. {Dissociating}.] [L. dissociatus, p. p. of
   dissociare to dissociate; dis- + sociare to unite, associate,
   socius companion. See {Social}.]
   To separate from fellowship or union; to disunite; to
   disjoin; as, to dissociate the particles of a concrete
   substance.

         Before Wyclif's death in 1384, John of Gaunt had openly
         dissociated himself from the reformer.   --A. W. Ward.

Source : WordNet®

dissociate
     v 1: part; cease or break association with; "She disassociated
          herself from the organization when she found out the
          identity of the president" [syn: {disassociate}, {divorce},
           {disunite}, {disjoint}]
     2: regard as unconnected; "you must dissociate these two
        events!"; "decouple our foreign policy from ideology"
        [syn: {decouple}] [ant: {associate}]
     3: to undergo a reversible or temporary breakdown of a molecule
        into simpler molecules or atoms; "acids dissociate to give
        hydrogen ions"