Source : Webster's Revised Unabridged Dictionary (1913)

Incoherence \In`co*her"ence\, Incoherency \In`co*her"en*cy\, n.
   [Cf. F. incoh['e]rence.]
   1. The quality or state of being incoherent; want of
      coherence; want of cohesion or adherence. --Boyle.

   2. Want of connection; incongruity; inconsistency; want of
      agreement or dependence of one part on another; as, the
      incoherence of arguments, facts, etc.

            Incoherences in matter, and suppositions without
            proofs, put handsomely together, are apt to pass for
            strong reason.                        --Locke.

   3. That which is incoherent.

            Crude incoherencies . . . and nauseous tautologies.
                                                  --South.

Source : WordNet®

incoherence
     n 1: lack of cohesion or clarity or organization [syn: {incoherency}]
          [ant: {coherence}]
     2: nonsense that is simply incoherent and unintelligible [syn:
        {incoherency}, {unintelligibility}]