A 'French' term typically defining a sexual liason between three persons, involving three
people engaged in sexual intimacy or sexual congress. Three
people having sexual relations with one another either randomly, such as on a one-time occassion, or regularly as long-term lovers. Three
people having sex together, typically at the same time in the same bed.
A favorite fantasy of men- that of being in bed with two women instead of just
one- but women also imagine bedding for sexual purposes with two men. Such is also known well enough between three
lesbian women, or between three homosexual men. As long as three
people are intimately/sexually involved, it is a 'manage-a-trois'.