- The state of cohabiting or living together as man and wife while not married.
- The state of being a concubine.
- 1902 Websters International Dictionary. "In some countries, concubinage is marriage of an inferior kind, or performed with less solemnity than a true or formal marriage; or marriage with a woman of inferior condition to whom the husband does not convey his rank or quality. Under Roman Law, it was the living together of a man and a woman in sexual relations without marriage but in conformity with local law."
the state of cohabitating while not married