It wasn’t invented to describe where Jews lived. The area that became the Jewish ghetto was the local foundry, that’s how it came to be known as the gheto even before it was the Jewish area.
Nowhere does it say the term ghetto was used to refer to that area before it was designated as the Jewish Ghetto. Perhaps the term Ghetto to refer to the Jewish Ghetto came from the foundry there, but that doesn't contradict what I said IMO.
For example, If a group of Romulans get relocated next to a marble factory, and for 200 years they are called as living in the
Romulan Marbhel. And then other poor neighborhoods start getting called the Marbhel, that term was created for them. It has a whole new meaning from anything before it and anyone else using the term, is taking a piece of Romulan culture.
