At what line do we call it Sex?

[Ozme52]

Intimacy is the key for me...

... but that word requires defining too.

[Synfall]

Always when I was younger I had considered full penetration with a dick as sex. Then I began to read smut and realized there is a gaping hole in that definition.
A man can penetrate a woman, and a man can penetrate a man. I found my full penetration theory rather flawed though, as by that definition lesbian couple never have sex.
I have yet to redefine my definition of what constitutes actual sex to my satisfaction.

[sipgirl]

Intimacy is the key for me...

... but that word requires defining too.

I agree wholeheartedly!!!