The term "hookup" and any conjugation of it are casually thrown around to describe a couple, threesome, or even more, having sex. It's called a "hookup" no matter if it's a heterosexual couple, a threesome, or even two couples who swap partners to have sex. But is the term "hookup" really the right term to describe sex?
Why it is:
When people have sex, it's a physical connection of usually two people (usually heterosexual) where there's been attraction and desire built up leading into it. Usually, in the concept of sex, a man's body enters a woman's body through the sex organs. This is the point where the bodies have "linked" together to form that actual physical connection.
Why it is not:
Physical connection aside, when a couple comes together, they had found each other somehow, whether it was through a dating site or if a wingman set up the couple to get together. Think about Tinder, or OKCupid, where the app 'matches you up' with people to see if the user feels the compatibility. If the user does, then the app has set up a match and an opportunity to go on a date. Even if it isn't a dating site or a wingman that sets the couple up, there's a way that they met. It could be at church, an extracurricular club, work, or a party. If somebody is interested in going to church, a friend of theirs will "hook them up" with the pastor to get them acclimated, or if a fraternity member's girlfriend wants to meet all of his fraternity brother and he obliges, then he'll "hook her up" with an administrative member to find a time to get it done.
Sex isn't the first priority here, even if it's the desired goal, and while it is not precluded, it is not something that is expected to be done immediately. Additionally, a "hookup" suggests that a couple sleeping together means they had sex. In a formal perspective, they're two different things. Yes, you can sleep with someone who you have sex with, but sleeping with someone does NOT mean that you had sex with them. Conversely, having sex with someone does NOT mean that you slept with that person. "Sleeping with" someone gets an added sexual connotation that isn't always there. All that sleeping with someone really is, is that they shared the same bed. Those two things get tied together but should not be.
In a Christian perspective, marriage is between one man and one woman, and no one else. The same applies with sex. In that case, sex is exclusive. Furthermore, sex is forbidden in the absence of marriage, so while a couple that is matched up could "hookup" in the end, they were not brought together necessarily for that purpose. In that situation, if they mutually decide to do the deed, they "hooked up" isn't the correct terminology. Sex is mutually consensual, where both parties have clear verbal agreement. A hookup may be mutually consensual but it's not anything serious.
Take a side: Is "hookup" the right term to describe sex? No.
Again, a hookup is not a serious affair. It's used to casually describe sex, but sex is not supposed to be casual. Sex is supposed to be a gift that comes from a successful relationship, and it's not something that should be taken for granted. It's not supposed to be casual like the term "hookup" is when applied to this context. The casual context also suggests that people "get around" but that just means he or she gets around and has sex with many people.
Sex is sex.
