Summa contra Gentiles1.35 Chapter XXXV. That the several names predicated of God are not synonymous

From what we have said it is also proved that, although names predicated of God signify the same thing, they are not synonymous, because they do not convey the same meaning.

For just as various things are by their various forms like one simple thing which is God, so our intellect, by its various conceptions, is somewhat like Him, in so far as it is led to know Him by the various perfections of creatures. Wherefore our understanding is neither false nor vain in conceiving many things of one; because that simple divine being is such that certain things can be likened to Him according to their manifold forms, as we have proved above. And according to its various conceptions our intellect devises various names which it applies to God. Wherefore, since they are not applied with the same meaning, it is clear that they are not synonymous, although they signify a thing absolutely one: for the name has not the same meaning, since it denotes the concept of the intellect previously to the thing understood.