toboe said:
Whether or not kissing is a psychological (i.e. mental) thing, it is definitely a physical thing, because it is a physical act that involves physical touching.

But it's not the physical sensation itself that's causing an orgasm. There's a significant distinction there. I'm not saying that kissing isn't a physical act. I'm saying that if you get off from kissing, it's for psychological reasons, not physical ones.

toboe said:
The dictionary defines sex as "Sexual interaction, usually involving vaginal and/or anal and/or oral penetration".

e621 doesn't have a different definition, so this might be a good one to go by.

There are two problems with this definition. The first is that it's recursive. "Sex: sexual interaction" doesn't actually do anything to define what sex is, it just pushes the problem back a notch. The second problem is that while it gives examples, those examples are not necessary, nor sufficient. Tribadism is considered sex, even though there's no penetration involved. Auto-fellatio is not considered sex, even though there's oral penetration.

Delian said:
Hmm, I wrote somewhat similar definition in forum #210782

Comparing to Clawdragons:
The two differences are, he mentions orgasm, but I mention genitals. I would argue that orgasm isn't necessary for sex. The other difference is, that I mention "sexual activity", which is more broad than sex.

I only noticed this now. Sorry.

The problem with sexual activity is described above - it's a recursive definition. But beyond that, I don't think genitals are necessary. I think most would consider, for instance, pegging to be a form of sex, but it doesn't involve the genitals.

On that note, I have an implication to suggest.