Bullying is a real, constant problem; it affects children and adults, individually and sometimes as a specific group. Ignoring when it happens, or what it is, doesn't help. Mislabeling other types of negative behaviour also doesn't help - it distracts from the real problem and the real victims, because it makes it look like a less serious problem than it actually is.
I wish to share some resources with everyone about bullying. Some are Canada-based (as am I), but they have definitions and good information on what bullying means, and what it does to people, in the short and long run. It also has resources to learn how to combat it, or to assist children and/or adults that are victims of bullying.
http://www.bullyingcanada.ca/what-is-bullying
http://www.prevnet.ca/bullying
http://www.bullyingendshere.ca/
http://www.prevnet.ca/bullying/facts-and-solutions
ETA: Fixed the links