Copacetic – Online Etymology Dictionary

We’re not quite sure where “copacetic” came from.

1919, but it may have origins in 19c. Amer.Eng. Southern black speech. Origin unknown, suspects include Latin, Yiddish (cf. Heb. kol b’seder), Italian, Louisiana French (coupe-sétique), and Native American. None is considered convincing by linguists.

While I’m on the topic, I should mention that the Online Etymology Dictionary is one of my favorite sites ever. I usually make a couple visits every day.
Copacetic – Online Etymology Dictionary