The ethnonym and autonym Slav denotes the Slavic peoples of Eastern and Southern Europe. It has been reconstructed in Proto-Slavic as ' (). The earliest written references to the Slav ethnonym are in other languages.
Possibly the oldest mention of Slavs in almost historical form is attested in Ptolemy's Geography (2nd century) as () and (), both listed as Scythian tribes living near Alanians north of Scythia (first roughly between Volga and Ural Mountains, second between the Baltic Sea and Black Sea). Zbigniew Goà Âàb accepted Pavel Jozef à  afárik's opinion that Greeks inserted or for Slavic (reconstructing Proto-Slavic '), and "through the labialized articulation of the vowel /ÃÂ/ conditioned by the preceding /uï/" in Proto-Slavic ' ().
() or was according to Eastern Roman/Byzantine scholar Procopius (500âÂÂ560) the old name of the Antes and Sclaveni, two Early Slavic branches. Procopius stated that the Sclaveni and Antes spoke the same language, but he traced their common origin back to not the Veneti (as per Jordanes) but a people that he called . He derived the name from Greek ('I scatter grain'), because "they populated the land with scattered settlements". He described their society as democratic, and their language as barbaric.
Jordanes wrote about the Slavs in his work (551): "although they derive from one nation, now they are known under three names, the Veneti, Antes and Sclaveni" (); in 19th century identified with the West Slavs, East Slavs, and South Slavs, a division based on the linguistic similarities between particular Slavic languages and dialects. He stated that the Veneti were the ancestors of the Sclaveni and the Antes, the two having used to be called but are now "chiefly" (though, by implication, not exclusively) called Sclaveni and Antes. Jordanes' and Procopius's were used for the ethnogenetic legend of the Slavs, the ancestors of the Slavs (the subsequent ethnic group name).
Thus, the Slav ethnonym at first denoted the southern group of the early Slavs. That ethnonym is attested by Procopius in Byzantine Greek as ('), ('), ('), ('), or ãúûñòá¿Âýÿù ('), while his contemporary Jordanes refers to the in Latin. In Ancient Greek there are no words with the root sl-, thus the original ethnonym was transformed into skl-, as that root was present (in , 'hard').
In East Church Slavonic manuscripts, the ethnonym is spelled (), such as in the Primary Chronicle, Sofia First Chronicle, Novgorod First Chronicle and Novgorod Fourth Chronicle. In the source dating to 898 included in the Primary Chronicle, the term is used both for East Slavic tribes and more often for a people (in the Kievan Rus' society, alongside Varangians, Chuds and Kriviches).
The origin of the Slavic autonym is disputed.
Other proposals for the etymology of propounded by some scholars have much less support. B. Philip Lozinski argues that the word once had the meaning of 'worshipper', in this context 'practicer of a common Slavic religion'; from that evolved into an ethnonym. S. B. Bernstein speculated that it derives from a reconstructed Proto-Indo-European , cognate to Ancient Greek (; 'population, people'), which itself has no commonly accepted etymology.
According to the widespread view, which has been known since the 18th century, the Byzantine (), (), borrowed from a Slavic tribe self-name *SlovÃÂne, turned into , (Late Latin sclÃÂvus) in the meaning 'prisoner of war slave', 'slave' in the 8th/9th century, because they often became captured and enslaved. However this version has been disputed since the 19th century.
An alternative contemporary hypothesis states that Medieval Latin via secondary form derives from Byzantine (, ) or (, ) with the meaning 'to strip the enemy (killed in a battle), to make booty, extract spoils of war'. This version is criticised as well.