Webster's Revised Unabridged Dictionary · 1913

Foursome

Foursome (fōr"sum) , adjective

[Four + 2d -some.]

Consisting of four; requiring four participants. [Scottish or Golf]

Foursome , noun

1.
(Golf) A game between four players, with two on each side and each side playing but one ball, the partners striking alternately. It is called a mixed foursome when each side consists of a man and a woman.
2.
A group of four people or objects; as, we need another player to make a foursome for bridge.