co·pa·cet·ic or co·pa·set·ic [kōpəˈsetik] adj. - very satisfactory or acceptable; fine.
Synonyms: satisfactory, acceptable, fine.
Etymology: 1919, but it may have origins in 19c. U.S. Southern black speech. Origin unknown, suspects include Latin, Yiddish (e.g. Hebrew kol b'seder), Italian, Louisiana French (coupe-sétique), and Native American. None is considered convincing by linguists.
Now that's an interesting etymology!