The Collaborative International Dictionary of English v.0.48:

Discord \Dis"cord`\, n. [OE. discord, descord, OF. discorde,
   descorde, F. discorde, from L. discordia, fr. discors,
   -cordis, discordant, disagreeable; dis- + cor, cordis, heart;
   cf. F. discord, n., and OF. descorder, discorder, F.
   discorder, to discord, L. discordare, from discors. See
   Heart, and cf. Discord, v. i.]
   1. Want of concord or agreement; absence of unity or harmony
      in sentiment or action; variance leading to contention and
      strife; disagreement; -- applied to persons or to things,
      and to thoughts, feelings, or purposes.
      [1913 Webster]

            A false witness that speaketh lies, and he that
            soweth discord among brethren.        --Prov. vi.
                                                  19.
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            Peace to arise out of universal discord fomented in
            all parts of the empire.              --Burke.
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   2. (Mus.) Union of musical sounds which strikes the ear
      harshly or disagreeably, owing to the incommensurability
      of the vibrations which they produce; want of musical
      concord or harmony; a chord demanding resolution into a
      concord.
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            For a discord itself is but a harshness of divers
            sounds m???ing.                       --Bacon.
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   Apple of discord. See under Apple.

   Syn: Variance; difference; opposition; contrariety; clashing;
        dissension; contention; strife; disagreement;
        dissonance.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Discord \Dis*cord"\, v. i. [OE. discorden, descorden, from the
   French. See Discord, n.]
   To disagree; to be discordant; to jar; to clash; not to suit.
   [Obs.]
   [1913 Webster]

         The one discording with the other.       --Bacon.
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WordNet (r) 3.0 (2006):

discord
    n 1: lack of agreement or harmony [syn: discord, strife]
    2: disagreement among those expected to cooperate [syn:
       discord, dissension]
    3: a harsh mixture of sounds [syn: discordance, discord]
    4: strife resulting from a lack of agreement [syn: discord,
       discordance]
    v 1: be different from one another [syn: disagree,
         disaccord, discord] [ant: agree, check,
         correspond, fit, gibe, jibe, match, tally]