Source : Webster's Revised Unabridged Dictionary (1913)

Irregularity \Ir*reg`u*lar"i*ty\, n.; pl. {Irregularities}. [Cf.
   F. irr['e]gularit['e].]
   The state or quality of being irregular; that which is
   irregular.

Source : WordNet®

irregularity
     n 1: behavior that breaches the rule or etiquette or custom or
          morality [syn: {abnormality}]
     2: not characterized by a fixed principle or rate; at irregular
        intervals [syn: {unregularity}] [ant: {regularity}]
     3: an irregular asymmetry in shape; an irregular spatial
        pattern [syn: {geometrical irregularity}]
     4: irregular and infrequent or difficult evacuation of the
        bowels; can be a symptom of intestinal obstruction or
        diverticulitis [syn: {constipation}]