Hobbes repeatedly expressed concerns about moral and political language, e.g., about the bad consequences of various uses and misuses of language. He did not simply focus on the consequences though. He also attempted to understand the problems, using the central semantic notion in his philosophy of language, signification. Hobbes, in both the Elements of Law and Leviathan, argues that a wide variety of terms – including ‘good’, ‘bad’, and the names of virtues and vices – have a double and inconstant signification. This paper explores and explains that theory of Hobbes's. (In the course of the discussion, two other interpretations of Hobbes's claims are discussed: Pettit’s discussion in terms of indexicals, and Alexandra’s in terms of sense and reference.) This phenomenon is, Hobbes thinks, pervasive in our use of moral and political language. Indeed he says his analysis applies to all “names of such things as affect us, that is, which please, and displease us” (Leviathan 4.24), which seems a very broad category indeed. This inconstancy of signification has considerable potential to cause confusion and conflict. Given those practical consequences, it is of some importance for Hobbes to find a solution to this problem. The paper examines several possible Hobbesian solutions to the problem. There is, however, reason to think that these suggested solutions cannot completely solve the problem. The paper concludes, then, by arguing that double and inconstant signification would always be a danger, even in a properly constituted Hobbesian commonwealth.