Source : Webster's Revised Unabridged Dictionary (1913)

Abnormality \Ab`nor*mal"i*ty\, n.; pl. {Abnormalities}.
   1. The state or quality of being abnormal; variation;
      irregularity. --Darwin.

   2. Something abnormal.

Source : WordNet®

abnormality
     n 1: an abnormal condition [syn: {abnormalcy}, {abnormal
          condition}] [ant: {normality}]
     2: retardation sufficient to fall outside the normal range of
        intelligence [syn: {mental defectiveness}]
     3: marked strangeness as a consequence of being abnormal [syn:
        {freakishness}]
     4: behavior that breaches the rule or etiquette or custom or
        morality [syn: {irregularity}]