abnormal vs irregular

abnormal is not a noun while irregular is a noun.

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

abnormal (noun)	irregular (noun)
	merchandise that has imperfections; usually sold at a reduced price without the brand name
	a member of an irregular armed force that fights a stronger force by sabotage and harassment

abnormal (adjective)	irregular (adjective)
not normal; not typical or usual or regular or conforming to a norm	contrary to rule or accepted order or general practice
departing from the normal in e.g. intelligence and development	(of solids) not having clear dimensions that can be measured; volume must be determined with the principle of liquid displacement
much greater than the normal	(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