Depends who you ask, since it's one of those terms they have been expanding the definition of so they could apply it to more people and ideas that they don't like. I just go by the self-evident meaning, the idea that white people should be supreme over non-white people. If I say "white supremacy", that's what I'm talking about. With other people, it can mean damn near anything these days, I've even seen it applied to the idea that people should try to show up to work on time.