Buddhism is considered a religion and does not fit that description.
Your emphatic capslock notwithstanding, there's no single defining element. See https://en.wikipedia.org/wiki/Religion
That's a can of worms. A pretty big one, actually.
https://buddhism-controversy-blog.com/2015/05/27/why-did-the...
"Religion" isn't a word in "most languages". "Religion" in English and the closely-related terms in closely-related languages may mean (or at least strongly imply) something like that (though with a god or God, specifically, not merely "a supernatural entity") simply because of the dominant belief systems to which the terms applied in the West (mostly, varieties of Near Eastern Monotheism), but even so they are frequently applied to systems from outside which don't have an "ordered belief in a supernatural entity", such as Confucianism.
> If it does become a synonym, then we'll simply need a NEW word to distinguish between "belief in supernatural entity" vs "no belief in a supernatural entity"
With, again, the caveat that it is more specific (referring to one or more gods, not merely any supernatural entities), we already have such a word, adopted specifically to focus in on that aspect and not the other elements of belief and practice which "religion" typically includes and may sometimes be used to refer to without an identifiable god anywhere in sight: "theism".
That is simply not true.
"Religion is a modern Western concept.[12] Parallel concepts are not found in many current and past cultures; there is no equivalent term for religion in many languages."
Ah, so there are entire cultures that are atheistic. Your argument has just achieved circularity!
Rather, in modern, western English we consider "religion" to mean that. Islam for examples uses the word 'Deen', the meaning of it includes how you looked at the world and your entire way of life.
Deen means basically exactly the stuff you say religion is not a synonym for :)
If you don’t believe we are zombies you hold a supernatural belief.
In most languages, "religion" will imply an ordered belief in a supernatural entity and set of accompanying practices.
It is NOT a synonym for all belief, philosophy, ethical framework, world paradigms, etc. If it does become a synonym, then we'll simply need a NEW word to distinguish between "belief in supernatural entity" vs "no belief in a supernatural entity"