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.
      [1913 Webster]

            Peace to arise out of universal discord fomented in
            all parts of the empire.              --Burke.
      [1913 Webster]

   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.
      [1913 Webster]

            For a discord itself is but a harshness of divers
            sounds m???ing.                       --Bacon.
      [1913 Webster]

   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.
   [1913 Webster]

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]

Moby Thesaurus II by Grady Ward, 1.0:

136 Moby Thesaurus words for "discord":
   Bedlam let loose, Discordia, Eris, animosity, antagonism,
   antipathy, argumentation, bedlam, blast, bobbery, brawl, brouhaha,
   cacophony, charivari, chirm, clamor, clangor, clap, clash,
   clashing, clatter, coarseness, collision, commotion, conflict,
   contention, contradiction, controversy, cracked voice, difference,
   din, disaccord, disaccordance, disaffinity, disagree, disagreement,
   discordance, discordancy, discrepancy, disharmony, disparity,
   dissension, dissent, dissidence, dissonance, disunion, disunity,
   divergence, diversity, divide, division, donnybrook, drunken brawl,
   dryness, dustup, enmity, faction, flap, fracas, free-for-all,
   friction, gruffness, gutturalism, gutturality, gutturalness,
   harshness, hell broke loose, hoarseness, hostility, howl, hubbub,
   hue and cry, hullabaloo, huskiness, inaccordance, incompatibility,
   incompatibleness, incongruity, inconsistency, inconsonance,
   inequality, inharmoniousness, inharmony, jangle, jar, jarring,
   loud noise, mischief, mismatch, negation, noise,
   noise and shouting, noncooperation, open conflict, opposition,
   oppugnancy, outcry, pandemonium, polarization, racket, rancor,
   raspiness, rattle, raucity, repugnance, rhubarb, roar, roughness,
   row, rub, ruckus, ruction, rudeness, rumble, rumpus, scrapiness,
   scratchiness, shindy, shivaree, stertorousness, strained relations,
   strife, tension, thickness, throatiness, thunder, thunderclap,
   tintamarre, tumult, ugliness, uncongeniality, unharmoniousness,
   unpleasantness, uproar, variance, vary