Menage a trois
A ménage à trois is a relationship or domestic arrangement in which three people, often a married couple and another lover, live together or are romantically or sexually involved. The French phrase literally translates as "household of three". In extended use, the term refers to any sexual act involving three people or Group sex.
Troilism or threesies is the name for the paraphilia relating to three-party sex.
As of 2019, no country allows both same-sex marriage and polygamy; therefore, if three people have a marital bond, this consists of two heterosexual marriages: of one person with two persons of the opposite sex. However, Dutch law allows for civil unions between more than two people. In September 2005, Victor de Bruijn formed a civil union with Bianca de Bruijn (to whom he was already married) and Mirjam Geven.
- Barbara Foster, Michael Foster, Letha Hadady. Three in Love: Ménage à trois from Ancient to Modern Times. ISBN 0595008070