bid adieu

Say goodbye, take leave of, as in It's beyond my bedtime, so I bid you all adieu, or I'll be glad to bid adieu to these crutches. French for “goodbye,” adieu literally means “to God” and was part of à dieu vous commant, “I commend you to God.” Adopted into English in the 1300s, it was first recorded in Chaucer's Troilus and Cressida (c. 1385). Today it is considered quite formal, although it also is used humorously.