n A person who is the property of another person and whose labor and also whose life often is subject to the owner's volition.
n A person who is legally obliged by prior contract (oral or written) to work for another, with contractually limited rights to bargain; an indentured servant.
n A person who is forced against his/her will to perform, for another person or other persons, sexual acts or other personal services on a regular or continuing basis.
n (engineering) A device that is controlled by another device.