Slurs are typically defined as conveying contempt based on group-membership. However, here I argue that they are not a unitary group. First, I describe two dimensions of variation among derogatives: how targets are identified, and how offensive the term is. This supports the typical definition of slurs as opposed to other derogatives. I then highlight problems with this definition, mainly caused by variable offence across slur words. In the process I discuss how major theories of slurs can account for variable offence, and conclude that contempt based on group-membership doesn’t cover all the data. I finish by noting that the most offensive slurs are those that target oppressed groups. I claim it is oppression that underpins most offence, and that beyond this offensive property, some slurs are actively used to oppress.