authoress vs author

authoress and author both are nouns.

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

As nouns, author is a hypernym of authoress; that is, author is a word with a broader meaning than authoress:

authoress: a woman author
author: writes (books or stories or articles or the like) professionally (for pay)

Other hypernyms of authoress include adult female, woman, writer.

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

authoress (verb)	author (verb)
	be the author of