Lockean slavery:

"Master and servant are names as old as history, but given to those of far different condition; for a freeman makes himself a servant to another, by selling him, for a certain time, the service he undertakes to do, in exchange for wages he is to receive: and though this commonly puts him into the family of his master, and under the ordinary discipline thereof; yet it gives the master but a temporary power over him, and no greater than what is contained in the contract between them. But there is another sort of servants, which by a peculiar name we call slaves, who being captives taken in a just war, are by the right of nature subjected to the absolute dominion and arbitrary power of their masters. These men having, as I say, forfeited their lives, and with it their liberties, and lost their estates; and being in the state of slavery, not capable of any property, cannot in that state be considered as any part of civil society; the chief end whereof is the preservation of property."

- John Locke [Second Treatise on Government]