Evil

All of these articles on the alignment system are going to be contentious, and this one is no exception.

Evil is, perhaps in the least controversial sense, the opposite of good. Augustine of Hippo argued that evil is not a thing in itself but rather is a privation of good. Thomas Aquinas agreed, writing in his Summa, "evil is the absence of the good."

If you put a gun to my head and made me give you my definition of evil, I would say something like: "Evil is that which violates the moral order of the universe."