Why do so many people refer the original Japanese versions as "subs"?

This is something that I have been wondering for the last days when I saw many anime fans keep referring the original Japanese versions as "subs", but I wonder why? For what I know there are a lot of anime (mostly obscure ones) that were uploaded in their original Japanese versions without any subs, which many people call it as "raw", but for me, using the word "subs" to refer any Japanese version of some anime does not make any sense since not all of the anime that exists are available in subs (both official and fan-made). As a person who have watched various anime in subs (mostly fan-subs), most of them weren't that well-made probably because some of those people who made those subs were not native English speakers, but I know there are fan-subs in other languages too, not just in English. Well, I have watched some anime in raw too and I'm fine with it 'cause I enjoyed some of the characters' voices in the original Japanese version, but I do still understand what is happening during the events of the episodes or pelikula even if I don't understand the language that much, but I know some of the meanings of the Japanese language and the same goes for the other languages too.