What is "belos"

Beloš (; fl. 1141–1163), was a Serbian prince and Hungarian palatine who served as the regent of Hungary from 1141 until 1146, alongside his sister Helena, mother of the infant King Géza II. Beloš held the title of duke (dux), and served as ban of Croatia from 1142 until 1158 and briefly in 1163. Beloš, as a member of the Serbian Vukanović dynasty, also briefly ruled his patrimony as the Grand Prince of Serbia in 1162. He lived during a period of Serbian-Hungarian alliance, amid a growing threat from the Byzantines, who had earlier been the overlords of Serbia.