Consistent, clear and comprehensive definitions of firearms, their parts andcomponents and ammunition in international instruments are necessary forstates to effectively address the complex transnational problem of firearmstrafficking. Frequently linked with organised crime, firearms trafficking hassignificant consequences for society and the economy at large. This articlelooks at the current international legal regime on gun control and thedefinitions contained within. An analysis of their scope and a comparisonwith regional definitions provides a critical look at the current landscapeof definitions addressing firearms trafficking. Controversies in theterminology of the definitions themselves, and the broader structure ofdefinitions in the international legal regime, undermine the internationalresponse to global firearms trafficking. A more comprehensive regime anddefinitions that allow for consistent implementation by states is necessaryto address this phenomenon.