Originally Posted by Marcus
Also, "quad" and "triad" suggest that all members are romantically involved with one another. What you described is a pair of couples who are dating each others spouses. Nothing wrong with it, just that calling it a "quad" confuses people like me who try to use words according to what they mean.
That is generally true of triads, but I don't think that is a hard and fast definition of a quad. It seems that most quads I read about (and the quad that appeared on Montel Williams) are just usually two couples intimately involved in each other's lives, with varying configurations of sexual involvement. Many, many quads just "swap" partners, but the women are not always sexually involved with each other. I believe that it is much rarer for all members of a quad to be sexually involved with each other.