I say to the title question, no: There is no agreed definition of what the hell terrorism is, so I can't say who is and isn't a terrorist -- a committer of terrorism -- is. The "Potter Stewart" approach may work in the SCOTUS and other settings where sound cases are presented, but it doesn't work on the street, at least not for me. Just as I can't call a someone a gigolo/harlot merely because I think they are or in some way resemble one, I can't just call someone (a group) a terrorist merely because they do things terrorists might and often enough also do. The epithet "terrorist" is becoming an easy aspersion, one bandied about far too casually. We've long observed instances of individuals or groups that were very violent and we didn't call them terrorists. We called them murderers or mass murderers or bombers, or whatever. "Terrorist" seems to be morphing into a catchall disparagement much like the "N-word," "F-word" and other terms variously have been. It should not. It needs to mean something specific. It needs to have real value, not merely be yet another term that means "all things evil and despicable that one can possibly be." Edit: Why have I remarked as I above have? Because I've seen, for instance the "N-word" by dint of its ubiquitous use in some quarters seemingly convert it into some sort of banal term, in some instances even a thoroughly neutral term. Now, that might be construed as a good thing, but for the fact that it remains also among the most disparaging things one can call another, it's not a "catchall" but rather a "be all" term -- as in it be all that can be wrong about one and one's character -- that when used as such, it necessarily refers to and draws its frame of comparative reference from one and only one genre of people and it's based on hateful and deeply held misrepresentations about them. When does the "N-word" not as readily apply? When the object of one's scorn isn't black, in which case the "F-word" becomes the alternative, and even that distinction accords a small measure of improvement over one's being a n*gger. About all that's worse is being both an "F" and an "N." It seems as though "terrorist" is headed in that direction, that is, in the direction of becoming banal, and then joining the lexicon of hurtful words people toss about. Do we really need more ways to asperse one another?