WordNet (r) 3.0 (2006):

break up
    v 1: to cause to separate and go in different directions; "She
         waved her hand and scattered the crowds" [syn: disperse,
         dissipate, dispel, break up, scatter]
    2: discontinue an association or relation; go different ways;
       "The business partners broke over a tax question"; "The
       couple separated after 25 years of marriage"; "My friend and
       I split up" [syn: separate, part, split up, split,
       break, break up]
    3: come apart; "the group broke up"
    4: break violently or noisily; smash; [syn: crash, break up,
       break apart]
    5: make a break in; "We interrupt the program for the following
       messages" [syn: interrupt, disrupt, break up, cut
       off]
    6: cause to go into a solution; "The recipe says that we should
       dissolve a cup of sugar in two cups of water" [syn:
       dissolve, resolve, break up]
    7: suffer a nervous breakdown [syn: crack up, crack, crock
       up, break up, collapse]
    8: take apart into its constituent pieces [syn: disassemble,
       dismantle, take apart, break up, break apart] [ant:
       assemble, piece, put together, set up, tack, tack
       together]
    9: destroy the completeness of a set of related items; "The book
       dealer would not break the set" [syn: break, break up]
    10: set or keep apart; "sever a relationship" [syn: sever,
        break up]
    11: attack with or as if with a pickaxe of ice or rocky ground,
        for example; "Pick open the ice" [syn: pick, break up]
    12: release ice; "The icebergs and glaciers calve" [syn:
        calve, break up]
    13: close at the end of a session; "The court adjourned" [syn:
        adjourn, recess, break up]
    14: bring the association of to an end or cause to break up;
        "The decree officially dissolved the marriage"; "the judge
        dissolved the tobacco company" [syn: dissolve, break up]
    15: come to an end; "Their marriage dissolved"; "The tobacco
        monopoly broke up" [syn: dissolve, break up]
    16: break or cause to break into pieces; "The plate fragmented"
        [syn: break up, fragment, fragmentize, fragmentise]
    17: cause to separate; "break up kidney stones"; "disperse
        particles" [syn: break up, disperse, scatter]
    18: separate (substances) into constituent elements or parts
        [syn: decompose, break up, break down]
    19: laugh unrestrainedly [syn: break up, crack up]

Moby Thesaurus II by Grady Ward, 1.0:

230 Moby Thesaurus words for "break up":
   ablate, accommodate, adapt, adjust, alter, ameliorate, amuse,
   analyze, anatomize, assay, atomize, be in stitches, beguile,
   better, bite the dust, break, break down, break into pieces,
   break open, break to pieces, burst, burst into laughter, burst out,
   burst out laughing, burst with laughter, bust a gut, cachinnate,
   cackle, canker, change, chortle, chuckle, come apart, come to dust,
   come unstuck, consume, convert, convulse, corrode, corrupt, crack,
   crack up, crash, crow, crumble, crumble into dust, crumble to dust,
   crunch, crush, cut to pieces, deactivate, debrief, decay,
   decompose, deform, delight, demob, demobilize, demolish, denature,
   detach, differ, differentiate, diffuse, disband, discharge,
   disintegrate, disjoin, disjoint, dismiss, disorganize, dispel,
   disperse, disrupt, dissect, dissent, dissever, dissolve, disunify,
   disunite, divaricate, diverge, diversify, divert, divide,
   effloresce, enliven, entertain, erode, exhilarate, fall,
   fall into decay, fall to dust, fall to pieces, fester, fission,
   fissure, fit, fracture, fracture one, fragment, gangrene, giggle,
   give away, give way, go bad, go into convulsions, go separate ways,
   go to pieces, grain, granulate, grind, guffaw, ha-ha, hee-haw,
   hee-hee, ho-ho, horselaugh, improve, kill, knock dead, laugh,
   laugh it up, laugh outright, let go, loosen up, make mincemeat of,
   meliorate, mildew, mince, mitigate, modify, modulate, mold, molder,
   mortify, muster out, mutate, nearly die laughing, necrose,
   overthrow, part, part company, powder, pulverize, putrefy,
   putresce, qualify, raise a laugh, raise a smile, rankle, re-create,
   realign, rebuild, reconstruct, recreate, redesign, reduce,
   reduce to elements, refit, reform, refresh, regale, relax, release,
   relieve, remake, renew, reshape, resolve, restructure, revamp,
   revive, ring the changes, roar, roar with laughter, rot, rupture,
   scatter, segment, separate, shake like jelly, shake with laughter,
   shatter, shift the scene, shiver, shout, shriek, shuffle the cards,
   slay, smash, smash up, snap, snicker, snigger, snort, solace,
   sphacelate, splinter, split, split up, split with laughter, spoil,
   spring a leak, squash, squish, start, subdivide, subvert, sunder,
   suppurate, tee-hee, tickle, titillate, titter, topple, tumble,
   turn the scale, turn the tables, turn the tide, turn upside down,
   variate, variegate, vary, waste away, wear away, work a change,
   worsen, wow, yuk-yuk