Robin - I think it's really funny that no one has responded to this question. It's a pretty tricky thing to answer when you get out of het definitions. I would like to think that sex is anytime that I engage in sexual energy with someone else. How to define that?

Making out may be passoinate, but it's not sex to me.

Touching of gentials isn't always inherently 'sex'. I tend to get naked (or mostly naked) when I have sex, so the removal of clothing for me tends to dictate the difference between making out and sex. I may reach around clothing if making out, but once the clothes are removed or in the case where the clothes stay on, then if penetration of any kind occures (oral, anal, vaginal), I would call that sex.

It's a tough one, and it really comes down to the exchange of energy involved. I had sex with a man a couple of weeks ago without penetration, but it was still sex to me because 1) we were naked and 2) we were exchanging sexual energies.