Balto-Slavic Syllabification: (Bal·to-Slav·ic)Pronunciation: /ˌbôltōˈslävik/Entry from US DictionaryDefinition of Balto-Slavic noun a branch of the Indo-European language family that includes the Baltic and Slavic languages. adjective relating to Balto-Slavic. Balto-Slavic in other Oxford dictionaries Definition of Balto-Slavic in the US English dictionary