The Collaborative International Dictionary of English v.0.48:

Discipline \Dis`ci*pline\, n. [F. discipline, L. disciplina,
   from discipulus. See Disciple.]
   1. The treatment suited to a disciple or learner; education;
      development of the faculties by instruction and exercise;
      training, whether physical, mental, or moral.
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            Wife and children are a kind of discipline of
            humanity.                             --Bacon.
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            Discipline aims at the removal of bad habits and the
            substitution of good ones, especially those of
            order, regularity, and obedience.     --C. J. Smith.
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   2. Training to act in accordance with established rules;
      accustoming to systematic and regular action; drill.
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            Their wildness lose, and, quitting nature's part,
            Obey the rules and discipline of art. --Dryden.
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   3. Subjection to rule; submissiveness to order and control;
      habit of obedience.
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            The most perfect, who have their passions in the
            best discipline, are yet obliged to be constantly on
            their guard.                          --Rogers.
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   4. Severe training, corrective of faults; instruction by
      means of misfortune, suffering, punishment, etc.
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            A sharp discipline of half a century had sufficed to
            educate us.                           --Macaulay.
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   5. Correction; chastisement; punishment inflicted by way of
      correction and training.
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            Giving her the discipline of the strap. --Addison.
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   6. The subject matter of instruction; a branch of knowledge.
      --Bp. Wilkins.
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   7. (Eccl.) The enforcement of methods of correction against
      one guilty of ecclesiastical offenses; reformatory or
      penal action toward a church member.
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   8. (R. C. Ch.) Self-inflicted and voluntary corporal
      punishment, as penance, or otherwise; specifically, a
      penitential scourge.
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   9. (Eccl.) A system of essential rules and duties; as, the
      Romish or Anglican discipline.

   Syn: Education; instruction; training; culture; correction;
        chastisement; punishment.
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The Collaborative International Dictionary of English v.0.48:

Discipline \Dis"ci*pline\, v. t. [imp. & p. p. Disciplined; p.
   pr. & vb. n. Disciplining.] [Cf. LL. disciplinarian to
   flog, fr. L. disciplina discipline, and F. discipliner to
   discipline.]
   1. To educate; to develop by instruction and exercise; to
      train.
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   2. To accustom to regular and systematic action; to bring
      under control so as to act systematically; to train to act
      together under orders; to teach subordination to; to form
      a habit of obedience in; to drill.
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            Ill armed, and worse disciplined.     --Clarendon.
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            His mind . . . imperfectly disciplined by nature.
                                                  --Macaulay.
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   3. To improve by corrective and penal methods; to chastise;
      to correct.
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            Has he disciplined Aufidius soundly?  --Shak.
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   4. To inflict ecclesiastical censures and penalties upon.

   Syn: To train; form; teach; instruct; bring up; regulate;
        correct; chasten; chastise; punish.
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WordNet (r) 3.0 (2006):

discipline
    n 1: a branch of knowledge; "in what discipline is his
         doctorate?"; "teachers should be well trained in their
         subject"; "anthropology is the study of human beings" [syn:
         discipline, subject, subject area, subject field,
         field, field of study, study, bailiwick]
    2: a system of rules of conduct or method of practice; "he
       quickly learned the discipline of prison routine"; "for such
       a plan to work requires discipline";
    3: the trait of being well behaved; "he insisted on discipline
       among the troops" [ant: indiscipline, undiscipline]
    4: training to improve strength or self-control
    5: the act of punishing; "the offenders deserved the harsh
       discipline they received" [syn: discipline, correction]
    v 1: develop (children's) behavior by instruction and practice;
         especially to teach self-control; "Parents must discipline
         their children"; "Is this dog trained?" [syn: discipline,
         train, check, condition]
    2: punish in order to gain control or enforce obedience; "The
       teacher disciplined the pupils rather frequently" [syn:
       discipline, correct, sort out]