Webster's 1828 Dictionary has an entry for "Adieu"; defines it as "farewell" or "commendation to the care of God."
Noah Webster, 1828 Webster's Dictionary, (The Editorium, 1828), "Adieu," accessed January 18, 2023
ADIEU', Adu'.
Farewell; an expression of kind wishes at the parting of friends.
ADIEU', noun A farewell, or commendation to the care of God; as an everlasting adieu