The Collaborative International Dictionary of English v.0.48:

Detach \De*tach"\, v. i.
   To push asunder; to come off or separate from anything; to
   disengage.
   [1913 Webster]

         [A vapor] detaching, fold by fold,
         From those still heights.                --Tennyson.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Detach \De*tach"\, v. t. [imp. & p. p. Detached; p. pr. & vb.
   n. Detaching.] [F. d['e]tacher (cf. It. distaccare,
   staccare); pref. d['e] (L. dis) + the root found also in E.
   attach. See Attach, and cf. Staccato.]
   1. To part; to separate or disunite; to disengage; -- the
      opposite of attach; as, to detach the coats of a bulbous
      root from each other; to detach a man from a leader or
      from a party.
      [1913 Webster]

   2. To separate for a special object or use; -- used
      especially in military language; as, to detach a ship from
      a fleet, or a company from a regiment.

   Syn: To separate; disunite; disengage; sever; disjoin;
        withdraw; draw off. See Detail.
        [1913 Webster]

WordNet (r) 3.0 (2006):

detach
    v 1: cause to become detached or separated; take off; "detach
         the skin from the chicken before you eat it" [ant:
         attach]
    2: separate (a small unit) from a larger, especially for a
       special assignment; "detach a regiment"
    3: come to be detached; "His retina detached and he had to be
       rushed into surgery" [syn: detach, come off, come away]
       [ant: attach]

Moby Thesaurus II by Grady Ward, 1.0:

113 Moby Thesaurus words for "detach":
   abstract, accredit, assign, authorize, break up, call up, cast off,
   charge, charter, commandeer, commission, commit, conscript,
   consign, cut off, deactivate, debrief, delegate, demob, demobilize,
   depute, deputize, detach for service, detail, devolute, devolve,
   devolve upon, disaffiliate, disassemble, disband, discharge,
   disconnect, disengage, disentangle, disintegrate, disjoin,
   dismantle, dismember, dismiss, dismount, disorganize, disperse,
   dissociate, dissolve, disunite, divorce, doff, draft, empower,
   enlist, enroll, entrust, free, give in charge, go separate ways,
   impress, induct, join, let go, levy, liberate, license, list,
   loose, loosen, mission, mobilize, muster, muster in, muster out,
   part, part company, post, press, raise, recruit, release, remove,
   scatter, send out, separate, sever, sign on, sign up, split up,
   summon, sunder, take apart, take off, transfer, unbar, unbind,
   unbolt, unbuckle, unbutton, unchain, unclasp, uncouple, undo,
   unfasten, unfetter, unglue, unlace, unlatch, unleash, unlock,
   unloose, unloosen, unstick, unstrap, untie, warrant,
   weigh anchor