From Late Latin sclavus or Sclavus, from Byzantine Greek Σκλάβος (Sklábos, “Slav”), which see for more. Compare Aromanian shcljau, Albanian shqa. The Romanian word seems to have preserved the original ancient ethnic meaning before it took on the sense of "slave" later on, which is the meaning found in the other Romance language descendants of the word, such as Italian schiavo. See also the borrowed neologism sclav, from the same source, and also slav.  Has also become a surname in Romanian.
șcheau m (plural șchei)