Good question. Then”Jewish” word is actually in Hebrew and is Shoah, which means catastrophe. This is the name “the Jews” use.

Holocaust has an ambiguous historical meaning with two parts. It was a sacrifice that was burned but also describes “how well” burned something gets. The burning has to be all the way. Beyond to a crisp. A Holocaust is burned all the way to ash so you can’t imagine what was there before. I think that’s appropriate for the level of genocide that was attempted.