The act of living with a woman to whom the man is not legally married. It is also used for a marriage with a woman of inferior condition (performed with less solemnity than the formal marriage, ) and to whom the husband does not convey his rank. As polygamy was sometimes practised by the patriarchs, it was a common thing to see one, two, or many wives in a family, and besides these several concubines, 2Sa_3:3, &c. 1Ki_11:3. 2Ch_11:21; but ever since the abrogation of polygamy by Jesus Christ, and the reduction of marriage to its primitive institution, concubinage has been forbidden and condemned among Christians.