Tribadism or tribbing is a form of mutual masturbation, sometimes called frottage, in which a woman rubs her vulva against her partner's body for sexual stimulation. The term is most often used in the context of lesbian sex, but is not exclusive to such. Tribadism sometimes involves female-to-female genital contact, but more often refers to a female rubbing her vulva against her partner's thigh, arm or stomach. Sometimes the labia majoras of one of the women's vulva will slip between her partner's labia majoras during lesbian sex. Tribadism can also refer to a masturbation technique in which a woman rubs her vulva against an inanimate object such as a bolster in an effort to achieve orgasm.