copesetic (adj.)

"fine, excellent, going well," 1919, but it may have origins in 19c. U.S. Southern black speech. Origin unknown; suspects include Latin, Yiddish (Hebrew kol b'seder), Italian, Louisiana French (coupe-sétique), and Native American. Among linguists, none is considered especially convincing. The popularization, and sometimes the invention, of the word often is attributed to U.S. entertainer Bill "Bojangles" Robinson (1878-1949).