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]

Moby Thesaurus II by Grady Ward, 1.0:

201 Moby Thesaurus words for "commitment":
   abandon, activity, affair, agency, agentship, agreement,
   allegiance, altruism, ardency, ardor, assigned task, assignment,
   attempt, authority, authorization, bounden duty, brevet, burden,
   business, call of duty, campaign, care, cause, charge,
   commendation, commission, commissioning, committal, committedness,
   consecration, consignment, constancy, contract, crusade, cure,
   deal, decidedness, decision, decisiveness, dedication, deference,
   definiteness, delegated authority, delegation, deputation,
   determinateness, determination, determinedness, devoir, devolution,
   devolvement, devotedness, devotion, devoutness, disinterest,
   disinterestedness, drive, duties and responsibilities, duty,
   earnestness, effort, embassy, empowerment, enfeoffment, engagement,
   enterprise, entrusting, entrustment, errand, ethics, executorship,
   exequatur, factorship, faith, faithfulness, fastness, fealty,
   fervency, fervidness, fervor, fidelity, fire, firmness, full power,
   great cause, hallowing, heartiness, heat, heatedness, homage,
   humility, impassionedness, imperative, infeodation, infeudation,
   intensity, intentness, interest, issue, jurisdiction, legation,
   license, lieutenancy, lifework, line of duty, loyalty, mandate,
   mass movement, mission, mittimus, modesty, movement, must, need,
   obligation, obstinacy, office, onus, operation, ordainment,
   ordination, ought, passion, passionateness, perseverance,
   persistence, place, plan, plenipotentiary power, power of attorney,
   power to act, preengagement, principle, procuration, program,
   project, proposition, proxy, purpose, purposefulness, purview,
   reason for being, recognizance, recommitment, regency, regentship,
   relegation, relentlessness, remand, remanding, resoluteness,
   resolution, resolve, resolvedness, respect, responsibility, right,
   sacrifice, self-abasement, self-abnegation, self-denial,
   self-devotion, self-effacement, self-forgetfulness,
   self-immolation, self-imposed duty, self-neglect,
   self-neglectfulness, self-renouncement, self-sacrifice,
   self-subjection, self-will, selflessness, seriousness, sincerity,
   single-mindedness, spirit, staunchness, steadfastness, task,
   tenacity, total commitment, tried-and-trueness, triedness,
   trueness, trust, trusteeship, unacquisitiveness, understanding,
   undertaking, unpossessiveness, unselfishness, vehemence, venture,
   verbal agreement, vicarious authority, warmth, warrant, will, work,
   zeal



Bouvier's Law Dictionary, Revised 6th Ed (1856):

COMMITMENT, criminal law, practice. The warrant. or order by which a court
or magistrate directs a ministerial officer to take a person to prison. The
commitment is either for further hearing, (q.v.) or it is final.
     2. The formal requisites of the commitment are, 1st. that it be in
writing, under hand, and seal, and show the authority of the magistrate, and
the time and place of making it. 3 Har. & McHen. 113; Charl. 280; 3 Cranch,
R. 448; see Harp. R. 313. In this case it is said a seal is not
indispensable.
     3. - 2d. It must be made in the name of the United States, or of the
commonwealth, or people, as required by the constitution of the United
States or, of the several states.
     4. - 3d. It should be directed to the keeper of the prison, and not
generally to carry the party to prison. 2 Str. 934; 1 Ld. Raym. 424.
     5. - 4th. The prisoner should be described by his name and surname, or
the name he gives as his.
     6. - 5th. The commitment ought to state that the party has been charged
on oath. 3 Cranch, R.448. But see 2 Virg. Cas. 504; 2 Bail. R. 290.
     7. - 6th. The particular crime charged against the prisoner should be
mentioned with convenient certainty. 3 Cranch, R. 449; 11 St. Tr. 304. 318;
Hawk. B. 2, c. 16, s. 16 Chit. Cr. Law, 110.
     8. - 7th. The commitment should point out the place of imprisonment,
and not merely direct that the party be taken to prison. 2 Str. 934; 1 Ld.
Ray. 424.
     9. - 8th. In a final commitment, the command to the keeper of the
prison should be to keep the prisoner "until he shall be discharged by due
course of law," when the offence is not bailable; when it is bailable the
gaoler should be, directed to keep the prisoner in his "said custody for
want of sureties, or until he shall be discharged by due course of law."
When the commitment is not final, it is usual to commit the prisoner "for
further hearing." The commitment is also called a mittimus. (q.v.)
    10. The act of sending a person to prison charged with the commission of
a crime by virtue of such a warrant is also called a commitment. Vide,
generally, 4 Vin. Ab. 576; Bac. Ab. h.t.; 4 Cranch, R. 129; 4 Dall. R. 412;
1 Ashm. R. 248; 1 Cowen, R. 144; 3 Conn. R. 502; Wright, R. 691; 2 Virg.
Cas. 276; Hardin, R. 249; 4 Mass. R. 497; 14 John. R. 371 2 Virg. Cas. 594;
1 Tyler, R. 444; U. S. Dig. h.t.