1595, from M.Fr.
debaucher "entice from work or duty," from O.Fr.
desbaucher "to lead astray," supposedly lit. "to trim (wood) to make a beam" (from
bauch "beam," from Frank.
balk; from the same Gmc. source that yielded Eng.
balk, q.v.). A sense of "shaving" something away, perhaps, but the root is also said to be a word meaning "workshop," which gets toward the notion of "to lure someone off the job;" either way the sense evolution is unclear.
"Debauchee, n. One who has so earnestly pursued pleasure that he has had the misfortune to overtake it." [Ambrose Bierce, "Devil's Dictionary," 1911]