Slavic (adj.)youdaoicibaDictYouDict[Slavic 词源字典]
1813; see Slav + -ic. Earlier in same sense was Slavonic (1640s), from Slavonia, a region of Croatia; Slavonian (1570s). As a noun in reference to a language group from 1812.[Slavic etymology, Slavic origin, 英语词源]