This article seeks to ameliorate the conceptual ambiguities surrounding the concepts of race, racialisation, and racism within Critical Terrorism Studies (CTS), as well as encourage the use of these concepts. Race is a key signifier in counter-terrorism discourse, yet its meaning is often taken for granted or left unexplored in CTS. Hence, this article proposes definitions of race, racialisation, and racism that make the concepts into an analytical lens. In developing these definitions, it employs a marginally adapted version of Gerring's criterial framework for concept formation. The article argues that the core attributes of the concepts race, racialisation, and racism are: (A) their socially constructed nature; (B) categorisation of a group as the "other"; (C) naturalisation; and (D) being concerned with community-like groups. The proposed definitions build on similarities and navigate differences in how the concepts are currently given meaning in CTS research. Considering that CTS is embedded in the context of 9/11, the concepts of race, racialisation, and racism may help to place counter-terrorism discourses and practices in a broader historical and political context and analyse the justifications supporting these discourses.