The Collaborative International Dictionary of English v.0.48:

Misunderstand \Mis*un`der*stand"\
   (m[i^]s*[u^]n`d[~e]r*st[a^]nd"), v. t. [imp. & p. p.
   Misunderstood (m[i^]s*[u^]n`d[~e]r*st[oo^]d"); p. pr. & vb.
   n. Misunderstanding.]
   To misconceive; to mistake; to miscomprehend; to take in a
   wrong sense.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Misunderstanding \Mis*un`der*stand"ing\, n.
   1. Mistake of the meaning; error; misconception. --Bacon.
      [1913 Webster]

   2. Disagreement; difference of opinion; dissension; quarrel.
      "Misunderstandings among friends." --Swift.
      [1913 Webster]

WordNet (r) 3.0 (2006):

misunderstanding
    n 1: putting the wrong interpretation on; "his misinterpretation
         of the question caused his error"; "there was no mistaking
         her meaning" [syn: misinterpretation, misunderstanding,
         mistaking]
    2: an understanding of something that is not correct; "he wasn't
       going to admit his mistake"; "make no mistake about his
       intentions"; "there must be some misunderstanding--I don't
       have a sister" [syn: mistake, misunderstanding,
       misapprehension]

Moby Thesaurus II by Grady Ward, 1.0:

73 Moby Thesaurus words for "misunderstanding":
   abuse of terms, agreement to disagree, argument, catachresis,
   clerical error, contorting, controversy, corrigendum,
   cross-purposes, difference, difference of opinion, difficulty,
   disagreement, discord, disparity, dispute, dissension, distortion,
   dividedness, division, eisegesis, erratum, error, failure, fault,
   faute, garbling, gloss, human error, malentendu, malobservation,
   misapplication, misapprehension, miscalculation, miscarriage,
   miscitation, misconception, misconstruction, miscount, misdeal,
   misexplanation, misexplication, misexposition, misidentification,
   misintelligence, misinterpretation, misjudgment, misplay, misprint,
   misquotation, misreading, misrendering, misreport, miss,
   misstatement, mistake, mistaking, mistranslation, misuse,
   misuse of words, odds, perversion, polarization, quarrel, rift,
   squeezing, torturing, twisting, typo, typographical error,
   variance, wrenching, wrong impression