bid adieu Say good-bye.

This  formulaic  farewell  uses  the  French  adieu, meaning “to God,” and has done so since Chaucer’s time. It is now considered rather formal, although it also is used humorously. In fact, humorist Charles Farrar  Browne, under  the  pen  name Artemus Ward, joked  about  it  back  in

1862: “I now bid you a welcome adoo” (ArtemusWard: His Book.The Shakers).