Toxic masculinity means different things for different people in different contexts. Within mainstream and in social media, toxic masculinity has come to be used as a catch-all term for harmful behaviours and attitudes of men informed by (hegemonic) masculinity, especially those related to power and inter-/intra-group conflict on the basis of gender (e.g., misogyny) and sexuality (e.g., homophobia). Whilst some research has begun to acknowledge the term’s utility in delineating culturally accepted and socially destructive aspects of hegemonic masculinity, there has not yet been an account of what toxic masculinity is and what it means. This chapter aims to provide an initial linguistic account of those aspects and behaviours that toxic masculinity is (and can be) used to refer to by investigating how it is used.