A lesbian is a woman who is attracted to other women. Two married women are in a lesbian relationship.
This is a word for women who are homosexual. Though homosexual women are often called gay, it's more common to call them lesbians. Lesbians are sexually attracted to other women. You can also use this word as an adjective. For example, a gay female director is a lesbian film maker. There could also be a book of lesbian fiction. This word comes from the name of the island of Lesbos, whose famous poet Sappho was believed to be a lesbian.