NaNoBloPo: Bullying - What is it really?

This isn't part of the original meme, but it is a proper blog.

So, let's talk about bullying. It's hard to ignore it, because everyone's talking about it these days; what it means, how to prevent it, will implementing experiments where kids have to shun one another help, etc.

Here's my question - what exactly constitutes bullying? In my opinion, the term can not only be overrused, but in fact, underused.
( When bullying's not the right word )

All thoughts are welcome!