authoritative vs official

authoritative is not a noun while official is a noun.

Word	Noun	Adjective	Verb	Adverb
authoritative	No	Yes	No	No
official	Yes	Yes	No	No

authoritative (noun)	official (noun)
	someone who administers the rules of a game or sport
	a worker who holds or is invested with an office

authoritative (adjective)	official (adjective)
endowed with authority	having official authority or sanction
having authority or ascendancy or influence	of or relating to an office
of recognized authority or excellence	verified officially
	(of a church) given official status as a national or state institution
	conforming to set usage, procedure, or discipline