irregular vs irregularity

irregular and irregularity both are nouns.

Word	Noun	Adjective	Verb	Adverb
irregular	Yes	Yes	No	No
irregularity	Yes	No	No	No

irregular (noun)	irregularity (noun)
merchandise that has imperfections; usually sold at a reduced price without the brand name	behavior that breaches the rule or etiquette or custom or morality
a member of an irregular armed force that fights a stronger force by sabotage and harassment	not characterized by a fixed principle or rate; at irregular intervals
	an irregular asymmetry in shape; an irregular spatial pattern
	irregular and infrequent or difficult evacuation of the bowels; can be a symptom of intestinal obstruction or diverticulitis

irregular (adjective)	irregularity (adjective)
contrary to rule or accepted order or general practice
(of solids) not having clear dimensions that can be measured; volume must be determined with the principle of liquid displacement
(used of the military) not belonging to or engaged in by regular army forces
deviating from normal expectations; somewhat odd, strange, or abnormal
failing to meet a standard of manufacture due to an imperfection
lacking continuity or regularity
not occurring at a regular rate or fixed intervals
independent in behavior or thought
(of a surface or shape); not level or flat or symmetrical