ménage à trois

noun

mé·​nage à trois mā-ˈnäzh-ä-ˈt(r)wä 

mə-

1

: an arrangement in which three people (such as a married couple and a lover of one member of the couple) have a sexual or romantic relationship especially while they are living together

2

: a sexual encounter involving three people : threesome

Word History

Etymology

French, literally, household for three

First Known Use

1856, in the meaning defined at sense 1