Threesome (noun)

1. A group of three people or things.
2. A sexual activity involving three people.

Origin:

Early 18th century: from three + -some.

Examples:

1. They went on a camping trip with a threesome of friends.
2. It was a threesome of musicians on stage.
3. The couple decided to spice up their relationship by inviting another person to their threesome.
4. He always dreamed of having a threesome with two women.
5. The threesome had a great time together, going out and partying every night.