Yours, Etc.: Origins and Uses of 8 Sign-Offs
c.1600, agent noun from admire (v.). "In common speech, a lover" [Johnson], a sense recorded from 1704.
early 15c. (implied in admired), from Middle French admirer (Old French amirer, 14c.), or directly from Latin admirari "to wonder at" (see admiration). Related: Admiring; admiringly.