Concubinage (noun)

The state or condition of living together as a sexual partner without being married.

Origin:

From the latin word concubinatus, meaning 'cohabitation'.

Examples:

1. Concubinage was a common practice in many cultures throughout history.
2. The society looked down upon concubinage and considered it immoral.
3. The king had many concubines, but only one official wife.
4. In some cultures, concubinage was accepted and even encouraged among the wealthy.
5. The relationship between the two was seen as concubinage, as they lived together without being married.