Grand Duke of Bosnia (Serbo-Croatian: veliki vojvoda rusaga bosanskog,[1]Latin: Bosne supremus voivoda / Sicut supremus voivoda regni Bosniae)[2][3] was a court title in the Bosnian medieval state, with its first holders being recorded around the middle of the 14th century. The title was bestowed by the monarch to its highest military commander, rarely two, usually reserved for the most influential and most capable among the highest most prominent Bosnian nobility highest Bosnian nobility.[4][5][6][7] It was very much different from the Grand duke title found in Europe at the time. To interpret it as an office post rather than a court rank could be equally accurate, and although it was retained for life by a nobleman who gained it, it was not meant to be hereditary, at least not at first. although it was not hereditary at first, it served both purposes and was retained for life by a nobleman who gained it. However, in the last several decades of the Bosnian medieval state it became hereditary, which means it became more than just an office or a court rank.[8][9]
^Fine, John Van Antwerp (1994). The Late Medieval Balkans: A Critical Survey from the Late Twelfth Century to the Ottoman Conquest. University of Michigan Press.