archduke n.

also archi-, word-forming element meaning "chief, principal; extreme, ultra; early, primitive," from Latinized form of Greek arkh-, arkhi- "first, chief, primeval," combining form of arkhos "a chief, leader, commander," arkhein "be first, begin" (see archon).

early 12c., "a sovereign prince," from Old French duc (12c.) and directly from Latin dux (genitive ducis) "leader, commander," in Late Latin "governor of a province," from ducere "to lead," from PIE root *deuk- "to lead." It is thus related to the second element in German Herzog "duke," Old English heretoga.

Applied in English to "hereditary nobleman of the highest rank" probably first mid-14c., ousting native earl. Also used to translate various European titles (such as Russian knyaz), usually of nobles ranking below a prince, but it was a sovereign title in some small states such as Burgundy, Normandy, and Lorraine.

1610s, "the wife of an archduke," modeled on French archiduchesse; see arch- "chief" + duchess. In later use generally "a princess of the reigning family of Austria," translating German Erzherzogin. Compare archduke, which is the masc. form.