This chapter studies Hobbes’s use of common language not only in his attacks on the “insignificant speech” of the scholastics but also in the definitions of his own philosophy. Thomas Hobbes was a careful observer of linguistic usage, appealing often to “what we are used to say.” But he does not accept “common usage” in any simple way. Like so many of his contemporaries, Hobbes was ambivalent about common language. As a move in his polemical invectives against scholastic language, Hobbes chose the side of “the people” who used language in a “natural” and “common” way. But common language also reflected patterns of thinking that Hobbes found deeply disturbing. Since for Hobbes everything hinges on the right understanding of words and well-explained definitions, he often claims to have common language at his side, yet we also find him subtly redefining terms to match his own philosophical views. The chapter explores Hobbes’s balancing act of revising ordinary language while playing down the revising act itself. In the last section the chapter suggests that the revision of common usage is part of Hobbes’s wider tactic to persuade the people that his civil science comes close to what every reasonable person should endorse.