A while ago, I got to wondering exactly what makes an orgy. For example, if fifteen people are all in a room having sex, but only within existing partnerships, and there's no "extra-partner" sex happening, is it an orgy? If four people are all fucking each other, is that an orgy, or is it just a foursome?

As it turns out, the dictionary is of little assistance with answering questions like this. I consulted a number of different dictionaries, and got a number of different answers--one said an orgy is five or more people having sex, one said more than two, one said an event dominated by "excessive" sexual activity (whatever that means), and so on.

I think three people having sex is a threesome; four people having sex is a foursome; it doesn't get to be an orgy until you've got five or more people.

But is a play party an orgy? Clearly not all orgies are play parties What about a play party where people aren't having penetrative sex? How about a mutual masturbation event...is that an orgy? My impulse is to say "no;" it isn't an orgy unless there are five or more people and there's more than mutual masturbation going on. There are, however, many kinds of sexual activities that aren't penetrative sex that I would consider to be an orgy, so I'm still not quite sure exactly where the borderline for the definition of "orgy" is.

So I started working on a Venn diagram of group sex. Then I started realizing that some of the potential overlaps are complicated beyond what you might at first think. For example, not all swing parties include group sex, yet most folks would probably think of a swing party as a group sex event.

Anyway, here's what I came up with. Mouse over the names of each category for a definition.