Yours, Etc.: Origins and Uses of 8 Sign-Offs
c.1200, "one of the parts into which something is divided;" mid-14c. as "action of distinguishing," from Old French distinction and directly from Latin distinctionem (nominative distinctio) "separation, distinction, discrimination," noun of action from past participle stem of distinguere (see distinguish). Meaning "distinctive nature or character" is late 14c. Meaning "excellence or eminence" (what distinguishes from others) is first recorded 1690s.