Outercourse is a broad term used to describe non-penetrative sexual activity. For instance, it is often used to describe frottage, or dry humping, which is when two people rub their naked or clothed genitals together for sexual stimulation. Outercourse can also be used to describe simulated sexual intercourse, such as mammary sex. Some people may even consider acts like oral sex, analingus, fingering, hand jobs and mutual masturbation to be outercourse as well.
Outercourse may also be called non-penetrative sex.