prematureness vs premature

prematureness is a noun but premature is not a noun.

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

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

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