1570s, "discharge of a number of guns at once," from French volee "flight" (12c.), from Vulgar Latin *volta, fem. noun from Latin volatum, past participle of volare "to fly" (see volant). Sporting sense of "a return of the ball before it hits the ground" (originally in tennis) is from 1851, from notion of hitting the ball in flight.
1590s, "discharge in a volley," from volley (n.). Sporting sense (originally in tennis) of "to return the ball before it has hit the ground" is from 1819. Related: Volleyed; volleying.