I. ˈthrēsəm noun
( -s )
Etymology: ME(Scots) thresum, from Middle English three, thre three + Middle English (northern dialect) -sum -some
1. : a group of three : trio
2. : a golf match in which one person plays his ball against the ball of two others playing each stroke alternately
II. adjective
: performed or engaged in by three persons
a threesome dance