The name Vuiko, which is also a personal name, has its variations among Serbs and Croats, where it is considered derived from the hypocorism Vuja. In Bulgarian, it is also considered to be derived from the archaism "vuyо," meaning "a child born after the children of an uncle," or as a wishful name with the idea of "May he live and become an uncle." In Ukrainian traditions, the anthroponym (V)Uiko is associated with the appellative "vuyko," which means "uncle, mother's brother." In Ukraine, especially in the west, names with the base Vuy- have often been used, and the word "vuyko" continues to be used as an appellative with a similar meaning. In the Carpathians, personal names with the bases Vuyk- / Vuin- have also been used since the 15th century. In Transcarpathia, the lexeme Vuiko could have been a personal name even in the 17th century. However, distinguishing between the appellative, personal, and nickname functions in ancient texts is sometimes challenging due to the influence of neighboring nations.