Modern historians of Greek slavery seem to agree, despite other differences, on an understanding of slavery as a relationship of property. This understanding of slavery essentially goes back to Aristotle's theory of natural slavery. An examination of the Greek vocabulary of slavery though shows that the vast majority of Greeks had a very different understanding of slavery as a relationship of domination. This article argues that this alternative Greek understanding of slavery can account for some serious conundrums in Greek attitudes and thought, and explains the reasons behind Aristotle's reformulation of slavery as a relationship of property. Finally, it is argued that seeing slavery as a relationship of domination has enormous potential for the modern study of slavery from a dynamic historical perspective.