It's hyper.

Hyper-Notorious Monsters not Highly Notorious Monsters.

It refers to the fact that they have a rage timer.

On Topic: We don't need many, and they've already said they're doing a roaming primal. Our instanced bosses are just fine right now, and the higher level NM's are enough like this. The respawn timer and high camp numbers just made it annoying to do and caused needless drama and gear restrictions. I enjoyed them in FFXI but IMO they have no place here other than some fringe ones.