To date, there has been a lack of consensus among researchers, practitioners, and laypersons about the definition of cyberbullying. Researchers have typically applied the key characteristics of intent to harm, power imbalance, and repetition from the definition of traditional bullying to cyberbullying, but how these characteristics transfer from the real world to a technology-mediated environment remains ambiguous. Moreover, very few studies have specifically investigated how cyberbullying is defined from the perspective of bullies, victims and bystanders. To this end, this article will propose a three-part definition of cyberbullying, which incorporates the perspective of bullies, victims and bystanders.