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]