mid-14c., from Old English Zefferus, from Latin Zephyrus (source also of French zéphire, Spanish zefiro, Italian zeffiro), from Greek Zephyros "the west wind" (sometimes personified as a god), probably related to zophos "the west, the dark region, darkness, gloom." Extended sense of "mild breeze" is c.1600. Related: Zephyrean.