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. (Two other interpretations are discussed: Pettit’s discussion in terms of indexicals, and Alexandra’s in terms of sense and reference.) 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 reason to think that these suggested solutions cannot completely solve the problem. Hobbes appears to believe that an appropriately powerful sovereign can resolve such problems when necessary, but this is a practical solution that relies on sovereign power, and the difficulty is never in principle resolved.