Human beings considered property, that is, slaves.
1863, Harper Twelvetrees, preface to The Story of the Life of John Anderson, the Fugitive Slave, William Tweedie (publisher), page ix:
Where is the man of intelligence who does not instantly see that this provision of human law […] makes the relation, between father and mother, that of mere agents for increasing the gains of him who claims a right of property in the human chattel, whose offspring, by law, are his?
