Author, n.
Etymology: [OE. authour, autour, OF. autor, F. auteur, fr. L. auctor, sometimes, but erroneously, written autor or author, fr. augere to increase, to produce. See Auction, n.]
1. The beginner, former, or first mover of anything; hence, the efficient cause of a thing; a creator; an originator. Eternal King; thee, Author of all being. Milton.
2. One who composes or writers a book; a composer, as distinguished from an editor, translator, or compiler. The chief glory every people arises from its authors. Johnson.
3. The editor of a periodical. [Obs.]
4. An informant. [Archaic] Chaucer.
1 other Webster entry under this spelling
Author, v. t.
1. To occasion; to originate. [Obs.] Such an overthrow . . . I have authored. Chapman.
2. To tell; to say; to declare. [Obs.] More of him I dare not author. Massinger.
Shades of meaning
Fernald has no entry of its own for author; he lists it under cause.
He lists it without comment; the entries above explain its neighbors.