Harry Potter question:?

It is because Harry's mother was never a pure blood witch. As you should know her family was muggle s therefore that is why Harry is only a half blood. Mud-blods are muggles that is why Voldemrt called her that but he also wasn't a pure blood. And as for your questin abut Harry's aunt saying about his mother being a witch well she wouldn't have known any different and would have just called her a witch. Hope this helps a bit!! I love Harry Potter!!('',)