The Collaborative International Dictionary of English v.0.48:

Disjoin \Dis*join"\ (d[i^]s*join"), v. t. [imp. & p. p.
   Disjoined (d[i^]s*joind"); p. pr. & vb. n. Disjoining.]
   [OF. desjoindre, F. disjoindre, d['e]joindre, fr. L.
   disjungere; dis- + jungere to join. See Join, and cf.
   Disjoint, Disjunct.]
   To part; to disunite; to separate; to sunder.
   [1913 Webster]

         That marriage, therefore, God himself disjoins.
                                                  --Milton.
   [1913 Webster]

         Never let us lay down our arms against France, till we
         have utterly disjoined her from the Spanish monarchy.
                                                  --Addison.
   [1913 Webster]

         Windmill Street consisted of disjoined houses.
                                                  --Pennant.

   Syn: To disunite; separate; detach; sever; dissever; sunder;
        disconnect.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Disjoin \Dis*join"\, v. i.
   To become separated; to part.
   [1913 Webster]

WordNet (r) 3.0 (2006):

disjoin
    v 1: make disjoint, separated, or disconnected; undo the joining
         of [syn: disjoin, disjoint] [ant: bring together,
         join]
    2: become separated, disconnected or disjoint [syn: disjoin,
       disjoint] [ant: conjoin, join]

Moby Thesaurus II by Grady Ward, 1.0:

114 Moby Thesaurus words for "disjoin":
   ablate, abrupt, alienate, analyze, anatomize, atomize, break,
   break off, break up, cast off, cast out, change, chop logic,
   come apart, consume, corrode, crack up, crumble, crumble into dust,
   cut adrift, cut off, cut out, decay, decompose, delete, depart,
   desynonymize, difference, differentiate, diffuse, disarrange,
   disarticulate, disconnect, discontinue, discriminate, disengage,
   disequalize, disintegrate, disjoint, disorganize, disperse,
   dissever, dissociate, dissolve, distinguish, disunite, diversify,
   divide, divorce, ease, ease off, eject, erode, estrange, expel,
   fall to pieces, fission, free, individualize, individuate,
   interrupt, isolate, leave, let go, let up, loose, loosen,
   make a distinction, mark, mark off, mark out, modify, molder, part,
   particularize, personalize, pull away, pull back, pull out,
   refine a distinction, relax, scatter, segregate, separate,
   sequester, set apart, set aside, set off, sever, severalize,
   shut off, slack, slack off, slacken, specialize, split,
   split hairs, stand aloof, stand apart, stand aside, step aside,
   subtract, sunder, throw off, throw out, uncouple, unglue, unleash,
   unstick, unyoke, vary, waste away, wear away, withdraw