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]

Moby Thesaurus II by Grady Ward, 1.0:

209 Moby Thesaurus words for "disintegrate":
   ablate, abrade, atomize, beat, bite the dust, blow to pieces,
   blow up, brain, bray, break, break down, break open,
   break to pieces, break up, brecciate, bring down, burn to death,
   burst, canker, carry away, cave in, cleave, collapse, come apart,
   come off, come to dust, come undone, come unstuck, comminute,
   conk out, consume, contriturate, corrode, corrupt, crack, crack up,
   crumb, crumble, crumble into dust, crumble to dust, crush,
   cut down, cut to pieces, deactivate, deal a deathblow, debrief,
   decay, decline, decompose, degenerate, deliquesce, demob,
   demobilize, demolish, descend, detach, disassemble, disband,
   discharge, disimprove, disjoin, dismantle, dismiss, disorganize,
   disperse, dissipate, dissolve, dissolve into chaos, droop, drop,
   effloresce, erode, fade, fail, faint, fall, fall into decay,
   fall off, fall to dust, fall to pieces, fell, fester, fission,
   fissure, fizzle out, flag, flour, fly apart, fracture, frag,
   fragment, gangrene, get loose, give away, give out,
   give the quietus, give way, go bad, go downhill, go separate ways,
   go soft, go to pieces, grain, granulate, granulize, grate, grind,
   grind to powder, gun down, hit the skids, incinerate, jugulate,
   languish, lapidate, lay low, let go, levigate, make mincemeat of,
   mash, mildew, mill, mold, molder, mortify, moulder, muster out,
   necrose, part, part company, peel off, peg out, pestle, peter out,
   pick to pieces, pine, pistol, poleax, poop out, pound, powder,
   pull in pieces, pull to pieces, pulverize, putrefy, putresce,
   rankle, reduce to powder, reduce to rubble, release, rend,
   retrograde, riddle, rot, rupture, scatter, scrunch, separate,
   shard, shatter, shoot, shoot down, shoot to death, shotgun, shred,
   silence, sink, slacken, smash, snap, sphacelate, split, split up,
   spoil, spring a leak, spring apart, squash, stab to death, start,
   stone, stone to death, strike dead, sunder, suppurate, taint,
   take apart, tear apart, tear to pieces, tear to shreds,
   tear to tatters, topple, total, triturate, tumble, turn, unbuild,
   undo, unmake, unravel, untune, vaporize, waste away, weaken,
   wear away, wear thin, wilt, worsen, wrack up, wreck, yield