Word Origin & History
1129, from O.Fr. duc and L. dux (gen. ducis) "leader, commander," in L.L. "governor of a province," from ducere "to lead," from PIE *deuk- "to lead" (cf. O.E. togian "to pull, drag," O.H.G. ziohan "to pull," O.E. togian "to draw, drag"). Applied in Eng. to "nobleman of the highest rank" probably first
c.1350, ousting native earl. Used to translate various European titles (e.g. Rus. knyaz).