"Cyberbullying" is when a child, preteen or teen is tormented, threatened, harassed, humiliated, embarrassed or otherwise targeted by another child, preteen or teen using the Internet, interactive and digital technologies or mobile phones. It has to have a minor on both sides, or at least have been instigated by a minor against another minor. Once adults become involved, it is plain and simple cyber-harassment or cyberstalking. Adult cyber-harassment or cyberstalking is never called cyberbullying.
Unfortunately sometimes the bully is hard to catch. For example, a student that builds a webpage remains anonymous and it is likely being hosted on a server in another state or even out of the country. The company hosting the webpage is not inclined to provide the name or remove it since Internet companies typically feel it is not their role to police the Internet.
If you or someone you know is being bullied make sure to keep as much documentation as possible. If it is in the form of email or IM it should be saved and printed. Consult with the school administration to determine what can be done. Also, keep in mind that bullying can take the form of cell phone text messages.