Femme is an adjective used to describe individuals in the gay, lesbian, bisexual, transgender, and cross-dressing communities that display feminine traits and behaviors. It's most commonly used to describe feminine lesbians, although others within GLBT circles, such as gay men, may also be described as femme. Femme lesbians are often called lipstick lesbians, while femme gay men are sometimes called flamers.
Femme comes from the French word which means woman. While technically an adjective, it's used as a noun by many people with feminine characteristics who classify themselves as femmes.
Femme is the opposite of butch, which concerns masculine identity.