In this article, we investigate the power of prevailing definitions within the research field of cyberbullying. We address how these definitions, mostly deriving from developmental psychology, have had a problematic influence on the way researchers, policymakers, practitioners working with interventions, and children and young people themselves approach the challenge of understanding and preventing cyberbullying and its consequences. We analyse how the definition of cyberbullying stemming from developmental psychology is inadequate in addressing the complexities of technologically mediated exclusionary processes in educational- and peer-group settings. The dominant research paradigm has suppressed such complexity by deeming irrelevant the extensive experience with cyberbullying of many children and young people. Thus, we argue that it is necessary for the research field to refine definitional work. Research on cyberbullying needs to draw on a broad spectrum of empirical data and incorporate multiple and diverse theoretical perspectives.