The Collaborative International Dictionary of English v.0.48:

Disintegrate \Dis*in"te*grate\, v. t. [imp. & p. p.
   Disintegrated; p. pr. & vb. n. Disintegrating.] [L. dis-
   + integratus, p. p. of integrare to renew, repair, fr.
   integer entire, whole. See Integer.]
   To separate into integrant parts; to reduce to fragments or
   to powder; to break up, or cause to fall to pieces, as a
   rock, by blows of a hammer, frost, rain, and other mechanical
   or atmospheric influences.
   [1913 Webster]

         Marlites are not disintegrated by exposure to the
         atmosphere, at least in six years.       --Kirwan.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Disintegrate \Dis*in"te*grate\, v. i.
   To decompose into integrant parts; as, chalk rapidly
   disintegrates.
   [1913 Webster]

WordNet (r) 3.0 (2006):

disintegrate
    v 1: break into parts or components or lose cohesion or unity;
         "The material disintegrated"; "the group disintegrated
         after the leader died" [ant: incorporate, integrate]
    2: cause to undergo fission or lose particles
    3: lose a stored charge, magnetic flux, or current; "the
       particles disintegrated during the nuclear fission process"
       [syn: disintegrate, decay, decompose]