The English word Slav could be derived from the Middle English word sclave, which was borrowed from Medieval Latin sclavus or slavus, itself a borrowing and Byzantine Greek σκλάβος sklábos "slave," which was in turn apparently derived from a misunderstanding of the Slavic autonym (denoting a speaker of their own languages). The Byzantine term Sklavinoi was loaned into Arabic as Saqaliba by who?