Why are STDs called STDs when "STDs" can be transmitted in ways NOT involving sex? At that point, it's just a transmitted disease if sex is?

STDs are things that you're FILLED with! Stop the fornication! Pervert!

Yeah, I sort of see what you mean, thing is, it's the most common way of transmitting it, and you know, it's gotten pretty bad now, more than a quarter of the world have something, AIDS, herpes, hep c or something. I mean you can get it from needles and blood or just touching something someone else touched if it's real contagious, but yeah, it's a worldwide health concern, and every and all means of preventing the spread need to be taken, for example needle exchanges, condoms, they have that where I am, and they don't even really have much drug use, or much sex for that matter, the education is important as well. They have drugs that can stop the spread of AIDS now, but they can't give them to everyone, and you know, if it keeps going like it is, half the world will have it, then it's not long before it's the whole world.

They are called STDs/STIs because they are usually transmitted via some sort of sexual contact. Kissing, oral sex, vaginal sex, anal sex, etc.

The diseases are transmittes through the swapping of bodily fluids (saliva, semen, vaginal discharge, blood).

That is why they are named as such.