noun
The originator or creator of a work, especially of a literary composition; or, one of the creators of a collaborative work.
(US copyright law) The initial owner of the copyright to a work, especially a work made for hire or a work of corporate authorship.
Someone who writes books for a living.
(obsolete, criminal law) Principal; the primary participant in a crime.
(archaic) One's authority for something: an informant.
(figurative) The creator or cause of anything.
verb
(chiefly US, sometimes proscribed) To create a work as its author.