Yiddish (n.)

1875, from Yiddish yidish, from Middle High German jüdisch "Jewish" (in phrase jüdisch deutsch "Jewish-German"), from jude "Jew," from Old High German judo, from Latin Iudaeus (see Jew). The English word has been re-borrowed in German as jiddisch. As an adjective from 1886. Related: Yiddishism.