A sexual partner, especially a woman, to whom one is not or cannot be married.
A slave-girl or woman, kept for instance in a harem, who is held for sexual service.
A woman who lives with a man, but who is not a wife.
A female partner in an unmarried romantic relationship.
A fellow gay man, especially a friend as opposed to a sexual partner.
A female friend.
A term of address for a female friend or among gay men.