Literally, to God, an ellipsis for I commend you to God: an expression of kind wishes at the parting of friends, equivalent to farewell; hence, a parting salutation in general: as, adieu to my hopes.Synonyms Adieu, Farewell, Good-by. These words have completely lost their original meanings. In use the difference between them is only one of formality, good-by being the most common, and adieu the most formal. By the Society of Friends (and perhaps some other sects) farewell is preferred, as not involving the careless mention of the name of God. In strict propriety, farewell is a parting salutation to persons going away.n. adieus or (in French spelling) adieux (a-dū z′ , ȧ-dyė′ ). A farewell or commendation to the care of God: as, an everlasting adieu; to make one's adieus.