Source : Webster's Revised Unabridged Dictionary (1913)

Adieu \A*dieu"\, interj. & adv. [OE. also adew, adewe, adue, F.
   ? dieu, fr. L. ad to + deus God.]
   Good-by; farewell; an expression of kind wishes at parting.

Adieu \A*dieu"\, n.; pl. {Adieus}.
   A farewell; commendation to the care of God at parting.
   --Shak.

Source : WordNet®

adieu
     n : a farewell remark; "they said their good-byes" [syn: {adios},
          {arrivederci}, {auf wiedersehen}, {au revoir}, {bye}, {bye-bye},
          {cheerio}, {good-by}, {goodby}, {good-bye}, {goodbye}, {good
         day}, {sayonara}, {so long}]
     [also: {adieux} (pl)]