Where does “slaaf” come from?

slaaf (Dutch) comes from Middle Dutch slave, from Late Latin Sclavus, from Byzantine Greek Σκλάβος, from Proto-Slavic slověninъ, from Proto-Slavic slovo, from Proto-Balto-Slavic ślawas, from Proto-Indo-European ḱléwos, from Proto-Indo-European ḱlew- — to cover; to incline.

slaaf (Dutch): slave