The Collaborative International Dictionary of English v.0.48:

committed \committed\ adj.
   1. Bound or obligated, as under a pledge to a particular
      cause, action, or attitude. Opposite of uncommitted.

   Note: [Narrower terms: bound up, involved, wrapped up;
         dedicated, devoted; pledged, sworn]
         [WordNet 1.5]

   2. Associated in an exclusive sexual relationship; also
      called attached. Opposite of unattached.

   Note: [Narrower terms: affianced, bespoken, betrothed,
         engaged, pledged, promised(predicate); married]
         [Also See: loving.]

   Syn: attached.
        [WordNet 1.5]

   3. Consigned involuntarily to custody, as in a prison or
      mental institution.
      [WordNet 1.5]