Is screaming at a fellow employee considered workplace violence?

It has been a long time since I have taken a class in workplace violence and am looking for clarification.

There is an employee who screamed at and berated another employee today. He was heard across the plant by others, which is a distance of about 90 feet. (This was in regard to work, not anything personal.) This is not the first time that he has done this, but no one has ever disciplined him about it. He has some bully tendencies and is the kind of person who believes that he is always right.

Their harassment policy refers to this kind of behavior, so we’re wondering how difficult it would be to terminate him. One concern is that the person he was screaming at this time may not be willing to take it to H.R. However, others heard this incident and the might be willing to speak up.

Any thoughts? Any experience with this? Any legal background about this that you can share?