I use "intercourse" as a larger category than just
sex. In fact, intercourse, in my usage, does not include the more
mundane forms of sex, such as
fucking.
William Gibson defined creativity as "rubbing two things together in a way that they haven't been rubbed together before."
To me, intercourse means this kind of rubbing, between two people. "A creative rubbing that changes both people." Making love is the best example. But it can also be a mind-blowing conversation, a shared perfect moment or, in extreme cases, just an exchange of looks.
Sometimes, when I think I'm just horny, an alernate form of intercourse will leave me satisfied.