This article is intended to examine the lines 1006a34-b9 of Metaphysics Γ 4, where Aristotle conjectures and discusses an objection to the very first step of his proof of the principle of the most universal science. As we shall see in detail, this objection consists in claiming that the meaning of a word is multiple, so that it is not possible for a word to have one single meaning, contrarily to what it seems to be required for one to say (...) something. As we shall also see, some crucial aspects of aristotelian notion of meaning emerge in this context, among which those related to the unity proper to it. (shrink)