Nonviolent Communication is a process developed by Marshall Rosenberg to continue the work of Mahatma Gandhi and Martin Luther King in the form of communication. Nonviolence, as Gandhi used the term, means something like: open heart and therefore no room for violence. The inverse then would be something like: closed heart and therefore room for harm.
Violence, as I see it, means any thought or action that moves toward human disconnection. If we then do what Rosenberg did and apply nonviolence to communication, we are aiming our communication towards human connection.