au·thor / ˈô[unvoicedth]ər/ (abbr.: auth.) • n. a writer of a book, article, or report. ∎  someone who writes books as a profession. ∎  the writings of such a person: I had to read authors I disliked. ∎ fig. an originator or creator of something, esp. a plan or idea: the authors of the peace plan.• v. [tr.] be the author of (a book or piece of writing): she has authored several articles on wildlife. ∎ fig. be the originator of; create: the concept has been authored largely by insurance companies.DERIVATIVES: au·tho·ri·al / ôˈ[unvoicedth]ôrēəl/ adj.ORIGIN: Middle English (in the sense ‘a person who invents or causes something’): from Old French autor, from Latin auctor, from augere ‘increase, originate, promote.’ The spelling with th arose in the 15th cent., and perhaps became established under the influence of authentic.

author originator, inventor; composer of a book, etc. XIV. ME. au(c)tour -AN. au(c)tour, OF. autor (mod. auteur) — L. auctor, -ōr-, f. auct-, augēre increase (cf. AUGMENT).
Hence authoress XV. So authority XIII. ME. autorite (hence authoritative XVII). authorize XIV.