Sextus Empiricus Pyrrhoniae Hypotyposes 2.22.256

[256] And we say much the same regarding the distinguishing of ambiguities. For if the Ambiguity is a word or phrase having two or more meanings, and it is by convention ¹ that words have meaning, then all such ambiguities as can be usefully cleared up—such, that is, as occur in the course of some practical affair— will be cleared up, not certainly by the dialectician, but by the craftsmen trained in each several art, as they have personal experience of the conventional way adopted by themselves of using the terms to denote the objects signified