A sexual activity in which one woman lies on top of another, often "scissoring" her legs with her partners', and moves rhythmically for mutual clitoral stimulation.

A sexual activity in which one woman lies on top of another and uses rhythmic movements for mutual clitoral stimulation.

Lesbianism; sometimes used specifically to describe sexual activity in which one women rubs another's pudenda with her thigh or with a dildo. The term originated with ancient Greeks.

An act of sexual stimulation between women, through the rubbing of external genitals against each another.

Tribadism or tribbing is female-to-female genital sex, sometimes called frottage.http://lesbianlife.about.com/od/lesbiansex/a/tribadismq.htm Lesbian Sex Question: Tribadism, accessed 18 Dec 2006. Two women rub their vulvae together, possibly to stimulate each other's clitoris to orgasm.