It's a word I'm pretty sure I've never heard before. I heard it for the first time on Thursday (from my boss's boss), and read it for the first time today on the BBC's Editors' blog.
Diaspora: the dispersion of Jews outside of Israel from the sixth century B.C., when they were exiled to Babylonia, until the present time.
i first learned the word from a Croatian friend back in uni, but not in reference to Jews.
a perhaps less common usage (though i didn't know about the Jewish-specific one til you mentioned it) is to refer to any people who have resettled elsewhere.
Per Merriam Webster:
2 a : the movement, migration, or scattering of a people away from an established or ancestral homeland b : people settled far from their ancestral homelands
on second thought, perhaps i didn't know about the Jewish tie-in because it's quite possible that in other languages it _only_ refers to the broader meaning. will have to investigate...
