1. A woman who lives with a man to whom she is not legally married; especially, one who is regarded as socially or sexually subservient; a mistress: Throughout history, there have been many situations when it was considered acceptable for an important man to keep a woman or women, whom he was not married to, as his concubines, and some of them were said to be treated better than the man’s wife.
2. In polygamous societies, a secondary wife, usually of inferior rank: Several concubines of the ancient lord worked in the kitchens and gardens.
3. A grown female who is held as a slave to a powerful man often for sexual purposes: The youngest concubine was an exquisite dancer and entertained the friends of her master.
4. Etymology: Latin concubina, from concumbere, "to lie with or together"; from com-, "together, with" plus cubare, "to lie down". Recognized by law among polygamous people as "a secondary wife".

Biblical References to Concubines

A concubine was a woman who had a marital (sexual) relationship with a man but she was secondary to the wife; that is, the concubine was not as high in the family status as the wife.

When barren wives; such as, Sara, Leah, and Rachel gave their handmaidens as surrogates (substitues) to their husbands to bear children; as indicated in Genesis 16:1-3; and Genesis 30:3-13; they were following a practice known from Babylonia (Code of Hammurabi, 144-145).

The children that Sarah and Rachel later bore inherited more than the children of the handmaidens, as indicated in Genesis 21:10-13 and Genesis 49:22-26 and which is also reflected in the Code of Hammurabi (170-171).