The train of thought I will follow here begins with two facts about Husserl. First, the main and most intractable problems in interpreting him, and the major conflicts between his interpreters, arise from and are fed by the equivocality and unsteady meaning of his terminology. Second, Husserl has a highly developed theory of terminology, beginning with, but by no means limited to, the earliest periods of his thought. This theory of terminology, moreover, focuses on the causes of equivocality and unsteadiness of meaning. These two facts, taken together, suggest why there is something philosophically deep, some deep aspect of the selfknowledge of knowledge, in Husserl’s work, and helps explains why figures of the stature of Heidegger and Carnap took so much interest in him. Nevertheless, I will suggest that Husserl’s theory of terminology is inadequate to his problems: that the self-knowledge of philosophy is here (as always) incomplete. This helps explain what both Heidegger and Carnap reject in Husserl, and therefore, in turn, why the question, how to give to or recover for terminology an unequivocal and fixed meaning, becomes crucial for both of them. Both of them, in fact, approach this question in a way which is essentially a modification—albeit a root and branch modification—of Husserl’s approach. This paper, despite it’s title, will be devoted mostly to setting up the problem in Husserl. At the end I will then briefly describe Heidegger’s and Carnap’s contrasting solutions.