The Collaborative International Dictionary of English v.0.48:

Dishonor \Dis*hon"or\ (d[i^]s*[o^]n"[~e]r or
   d[i^]z*[o^]n"[~e]r), v. t. [imp. & p. p. Dishonored
   (d[i^]s*[o^]n"[~e]rd or d[i^]z*[o^]n"[~e]rd); p. pr. & vb. n.
   Dishonoring.] [OE. deshonouren, F. d['e]shonorer; pref.
   d['e]s- (L. dis-) + honorer to honor, fr. L. honorare. See
   Honor, v. t.] [Written also dishonour.]
   1. To deprive of honor; to disgrace; to bring reproach or
      shame on; to treat with indignity, or as unworthy in the
      sight of others; to stain the character of; to lessen the
      reputation of; as, the duelist dishonors himself to
      maintain his honor.
      [1913 Webster]

            Nothing . . . that may dishonor
            Our law, or stain my vow of Nazarite. --Milton.
      [1913 Webster]

   2. To violate the chastity of; to debauch. --Dryden.
      [1913 Webster]

   3. To refuse or decline to accept or pay; -- said of a bill,
      check, note, or draft which is due or presented; as, to
      dishonor a bill exchange.

   Syn: To disgrace; shame; debase; degrade; lower; humble;
        humiliate; debauch; pollute.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Dishonor \Dis*hon"or\ (d[i^]s*[o^]n"[~e]r or
   d[i^]z*[o^]n"[~e]r), n. [OE. deshonour, dishonour, OF.
   deshonor, deshonur, F. d['e]shonneur; pref. des- (L. dis-) +
   honor, honur, F. honneur, fr. L. honor. See Honor.]
   [Written also dishonour.]
   [1913 Webster]
   1. Lack of honor; disgrace; ignominy; shame; reproach.
      [1913 Webster]

            It was not meet for us to see the king's dishonor.
                                                  --Ezra iv. 14.
      [1913 Webster]

            His honor rooted in dishonor stood.   --Tennyson.
      [1913 Webster]

   2. (Law) The nonpayment or nonacceptance of commercial paper
      by the party on whom it is drawn.

   Syn: Disgrace; ignominy; shame; censure; reproach;
        opprobrium.
        [1913 Webster]

WordNet (r) 3.0 (2006):

dishonour
    n 1: a state of shame or disgrace; "he was resigned to a life of
         dishonor" [syn: dishonor, dishonour] [ant: honor,
         honour, laurels]
    2: lacking honor or integrity [syn: dishonor, dishonour]
       [ant: honor, honour]
    v 1: bring shame or dishonor upon; "he dishonored his family by
         committing a serious crime" [syn: dishonor, disgrace,
         dishonour, attaint, shame] [ant: honor, honour,
         reward]
    2: force (someone) to have sex against their will; "The woman
       was raped on her way home at night" [syn: rape, ravish,
       violate, assault, dishonor, dishonour, outrage]
    3: refuse to accept; "dishonor checks and drafts" [syn:
       dishonor, dishonour] [ant: honor, honour]