1690s, French, "good-bye for now," literally "to the seeing again." From au "to the" (see au) + revoir "see again, see in turn" (Old French reveoir, 12c.), from Latin revidere, from re- "back, again" (see re-) + videre "to see" (see vision).
*au-
au courant
au fait
au naturel
au pair
au revoir
aubade
aubaine
auberge
aubergine
Aubrey