Frottage refers to the act of rubbing body parts together for the purpose of sexual stimulation. The act of frottage usually involves two partners rubbing their genitals together, but it does not always have to involve genital contact of both partners. For instance, mammary intercourse, in which a man rubs his penis between a woman's breasts, can also be considered frottage. The word frottage is derived from the French word frotter, which means to rub.
When clothed couples engage in frottage, it is often referred to as dry humping.