What is the meaning of Concubine?

A sexual partner, especially a woman, to whom one is not or cannot be married.

A woman who lives with a man, but who is not a wife.

A slave-girl or woman, kept for instance in a harem, who is held for sexual service.

concubine

female partner in a common-law marriage

cohabitant, female domestic partner

concubine

plural of concubina

vocative singular of concubīnus

A concubine; a secondary female partner.

A illegitimate or unacknowledged partner (male or female)

Source: wiktionary.org