there is more than one definition. Just because thats how its being used now, doesnt mean that exactly the definition. The definition is always changing when they want to fit it for a purpose.
Ex:
so by your thoughts a terrorist is anyone who kills someone else? I think you are making this something it isnt, he wasnt a terrorist he was a cold blooded killer. Please tell me where he stated a purpose political, religious or otherwise. He was picked on, he didnt like people and he was delusional. Sorry he is just another wacko, although if you really need him to be, you can classify him however you wish.