Femi(ni)cide is the most extreme form of intersectional violence against women and girls. Practices of defining and classifying the killing of women because of their gender have been varied, complex, challenging, and taxing. This chapter asks how femi(ni)cide came to be by tracing its emergence, classification, and movement across scales. Drawing on an archaeological method (Foucault, 1972), time and space become the compasses that guide the analysis for grasping critical moments in the meaning-makings of femi(ni)cide that are calcified in policies, reports, resolutions, papers, and databases, amongst other forms of knowledge production. Given the scope of this handbook, this chapter follows and analyses a multiplicity of efforts from different world regions. Rather than affirming a position, the aim is to illustrate the different approaches to femi(ni)cide. The chapter contributes to the sociology of knowledge and science and technology studies (STS) as it advances current theorisations of femi(ni)cide by understanding it as a boundary object. Building on this, six epistemic worlds that dispute and negotiate the meaning-makings of femi(ni)cide are described: the institutional, the social, the legal, the criminological, the statistical, and the theoretical. It is recognised that the borders of these epistemic worlds are not fixed and that actors can simultaneously take part in many. Four main affordances of femi(ni)cide as boundary object are assessed: porosity, materiality, topology, and friction. The chapter concludes that tracing femi(ni)cide as such allows us to see changes, expansions, and variations; places relationality at the core; and repurposes it as a matter of care.