The word slave, ever important after it entered English in the mid sixteenth century, comes from the French word sclave, from the Latin word sclavus. Both of these words also meant "slave", but the latter originally meant "Slav" (as in the group of people indigenous to eastern Europe), because the Romans originally enslaved, well, Slavs. This is from the Greek word sklabos, from earlier slabenos, from Old Church Slavonic sloveninu, from Proto-Slavic slovenin, which may have several origins, all of them Slavic as well. Indeed, the word Slav followed a similar path into English, all the way up through sclavus and then directly into Middle English sclave before today. The word Yugoslavia means "land of the southern Slavs" (Yugo is from Serbian jugo, from Proto-Slavic jugb and maybe PIE hewg, still "south"). Anyway, the point of all this is that slave meant slav. Whoa.
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.