Organon

THINGS are termed homonymous, of which the name alone is common, but the definition (of substance according to the name) is different; thus "man" and "the picture of a man" are each termed "animal," since of these, the name alone is common, but the definition (of the substance according to the name) is different: as if any one were to assign what was in either, to constitute it "animal," he would allege the peculiar definition of each. But those are called synonyms, of which both the name is common, and the definition (of the substance according to the name) is the same, as both "a man" and "an ox" are "animal," for each of these is predicated of as "animal" by a common name, and the definition of the substance is the same, since if a man gave the reason of each as to what was in either, to constitute it "animal," he would assign the same reason.