immature vs newborn

immature is not a noun while newborn is a noun.

Word	Noun	Adjective	Verb	Adverb
immature	No	Yes	No	No
newborn	Yes	Yes	No	No

immature (noun)	newborn (noun)
	a baby from birth to four weeks

immature (adjective)	newborn (adjective)
not yet mature	having just or recently arisen or come into existence
characteristic of a lack of maturity	recently born
(used of living things especially persons) in an early period of life or development or growth
(of birds) not yet having developed feathers
not fully developed or mature; not ripe