premature vs prematureness

premature is not a noun while prematureness is a noun.

Word	Noun	Adjective	Verb	Adverb
premature	No	Yes	No	No
prematureness	Yes	No	No	No

premature (noun)	prematureness (noun)
	the state of being premature

premature (adjective)	prematureness (adjective)
born after a gestation period of less than the normal time
uncommonly early or before the expected time
too soon or too hasty