Yep, the baby boom happened in many places... the term 'baby boom' and 'baby boomer' and then 'boomer' are very much US-centric if you look through newspapers, academic publications.

Also... you're telling me your French speaking parents referred to them as 'baby boomers', as in... a loan word, from English, as opposed to something that might more naturally arise from French?

bébé d'expansion?

Granted, I do not speak French, that particular guess may be wildly unrealistic in some way, but I would think that general linguistic and etymylogical concepts apply generally.

https://www.etymonline.com/fr/word/baby%20boom

Assuming google translate is doing a decent job of translating that to English for me, I am fairly confident this literally says the French term "baby-boom(er)" is a loan term, from English, specifically from the US.

Anyway, I am not saying that people should not be free to use or adapt terms from other languages, that would be stupid and also impossible to enforce, especially stupid coming from an English speaker such as myself, with English essentially being a bastard mutant step child of at least three different languages smashing into each other.

I would be unable to go to the karaoke bar, sing a song about a latent gestalt consciousness, grab a bahn mi to much on, and then further discuss the relative 'lingua franca' status of varying languages of the world, all whilst doing my best to stave off ennui.

What I am saying is that criticizing my US Centric definition of a US Centric term on the grounds that the definition itself is too US Centric... that is stupid.

.........

Is 'millennial' a commonly used generational cohort word present in many languages right now?

Of course.

However... I would argue my definition still holds.

If you can remember 9/11 happening, generally, you are some kind of a millenial, you would identify as such, you would use that term.

Yep, 9/11 happened to the US.

And it was the biggest news story on the planet at the time.

Governments around the world reached out to the US with formal announcements of sympathy.

Newscasters and print media ran the story for days, weeks, in many countries.

It was a pretty big deal, the world hegemon having its financial center directly attacked.

Markets all the world freaked out, to varying degrees.

And I could casually argue that generally, roughly, though of course not as directly traumatizing to non USAmericans, it was a bigger deal in countries that were culturally/economically connected to the US, and thus inhabitants of those countries were/are more likely to later use a fairly direct equivalent of 'millennial' as a generational cohort term... as a loan word, from our media's intial popularization of the term, to decry our avocado toast habits and whichever stagnant and poorly operated line of shitty franchise restaurants we are apparently responsible for murdering.

Why not use the local language word for 'millenium' as a basis, instead of adopting one from English?

But to further nuance this, I am sure you would point out that the English word millennial is of French origin, and you would be correct.

So sure, this obviously makes more sense as a wholly and truly French word, we English speakers did after all, more or less borrow something like 70% of our vocabulary from French.

But then we can refer back to my actual proposed definition:

I bet you do actually remember 9/11 being on the TV, in the papers, being discussed, to at least degree, if you are a millennial, who speaks French, and was roughly 5 years old or older, in France, when it happened.

If I am wrong about that, please let me know.