The Collaborative International Dictionary of English v.0.48:

Commitment \Com*mit"ment\, n.
   1. The act of committing, or putting in charge, keeping, or
      trust; consignment; esp., the act of committing to prison.
      [1913 Webster]

            They were glad to compound for his bare commitment
            to the Tower, whence he was within few days
            enlarged.                             --Clarendon.
      [1913 Webster]

   2. A warrant or order for the imprisonment of a person; --
      more frequently termed a mittimus.
      [1913 Webster]

   3. The act of referring or intrusting to a committee for
      consideration and report; as, the commitment of a petition
      or a bill.
      [1913 Webster]

   4. A doing, or perpetration, in a bad sense, as of a crime or
      blunder; commission.
      [1913 Webster]

   5. The act of pledging or engaging; the act of exposing,
      endangering, or compromising; also, the state of being
      pledged or engaged. --Hamilton.
      [1913 Webster]

WordNet (r) 3.0 (2006):

commitment
    n 1: the trait of sincere and steadfast fixity of purpose; "a
         man of energy and commitment" [syn: committedness,
         commitment]
    2: the act of binding yourself (intellectually or emotionally)
       to a course of action; "his long commitment to public
       service"; "they felt no loyalty to a losing team" [syn:
       commitment, allegiance, loyalty, dedication]
    3: an engagement by contract involving financial obligation;
       "his business commitments took him to London"
    4: a message that makes a pledge [syn: commitment,
       dedication]
    5: the official act of consigning a person to confinement (as in
       a prison or mental hospital) [syn: commitment, committal,
       consignment]