authorial vs author

authorial is not a noun while author is a noun.

Word	Noun	Adjective	Verb	Adverb
authorial	No	Yes	No	No
author	Yes	No	Yes	No

authorial (noun)	author (noun)
	writes (books or stories or articles or the like) professionally (for pay)
	someone who originates or causes or initiates something

authorial (adjective)	author (adjective)
of or by or typical of an author

authorial (verb)	author (verb)
	be the author of