you're kidding, right? this needs a definition? it is not patently obvious? like pornography, do we not know it when we see it? the downside to context is it presumes that at some point in time/location some behavior is going to be acceptable by a group of observers. when it comes to:
hitting, "simulated" drowning, electrocution, slapping, sonic assault, microsecond burning by microwave transmission, exposure to extreme heat and cold, etc., no definition is going to change the impact of these behaviors, regardless of what any observer says, thinks or defines what is happening. i think it is pretty clear that virtually all biological organisms with a nervous system would experience any/all of the above as painful.
if you (or others) would like empirical evidence of the impact of these behaviors on human beings, read this.
calling the death of people due to the impact of a bomb "collateral damage" does nothing to alter the absolute outcome of the bomb on the people -- they remain dead.