prehistory vs prehistoric

prehistory is a noun but prehistoric is not a noun.

Word	Noun	Adjective	Verb	Adverb
prehistory	Yes	No	No	No
prehistoric	No	Yes	No	No

prehistory (noun)	prehistoric (noun)
the time during the development of human culture before the appearance of the written word

prehistory (adjective)	prehistoric (adjective)
	of or relating to times before written history
	belonging to or existing in times before recorded history
	outdated