crooked vs irregular

crooked is not a noun while irregular is a noun.

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

crooked (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

crooked (adjective)	irregular (adjective)
having or marked by bends or angles; not straight or aligned	contrary to rule or accepted order or general practice
not straight; dishonest or immoral or evasive	(of solids) not having clear dimensions that can be measured; volume must be determined with the principle of liquid displacement
irregular in shape or outline	(used of the military) not belonging to or engaged in by regular army forces
having the back and shoulders rounded; not erect	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