Source : Webster's Revised Unabridged Dictionary (1913)

Malformation \Mal`for*ma"tion\, n. [Mal- + forniation.]
   Ill formation; irregular or anomalous formation; abnormal or
   wrong conformation or structure.

Source : WordNet®

malformation
     n 1: an affliction in which some part of the body is misshapen or
          malformed [syn: {deformity}, {misshapenness}]
     2: something abnormal or anomalous [syn: {miscreation}]