Sometimes I think zoon logon echon should be translated more literally as “talking animal” rather than the classic “rational animal”. (Perhaps “animal” should be “living being”, but here I am not worried about discrimination against plants.) Logos was a highly overdetermined word that could also mean word, ratio, measure, or principle, as well as language or reason, but the linguistic meanings seem to be more primary. Within the Aristotelian corpus there are several longer alternate phrasings, of which some stress the linguistic aspect and others the rational aspect. (The human being is said to be a “political” animal as well.)
I don’t think Aristotle imagined human reason to be separable from some articulation in language. Thus I disagree with those who want to interpret nous (classically , “intellect”) as some kind of originary intuition. This seems to me very alien to Aristotle’s whole way of approaching things. (Plotinus did explicitly treat nous as something like intellectual intuition, and had major influence on later readers of Aristotle. I do think there is such a thing as intuition, but it is not a kind of knowledge and it is not originary.)
Echon is literally “having”, which applies better to the linguistic interpretations of logos, whereas philosophically speaking we don’t strictly have reason as a full possession, but rather a potential for it.
That said, “rational animal” accurately conveys our two-sided nature. We are animals, and because we have language, we can potentially participate in reason.
But regardless of how well we do or do not take care of things, this has the effect of making us ethical beings. Who we are will turn out to be more than anything a matter of the commitments we make. This is transforming.
Incidentally, nothing about this says anything that singles out our particular kind of ape. It just happens that we only know of one biological species that meets this very abstract definition, but this is a merely contingent truth. So, all the talking species in science fiction would be human to Aristotle if they were real, and if we could prove that dolphins had a comparable linguistic ability, they would be human, too. (See also What Is “I”?; Psyche, Subjectivity; Individuation; Happiness; Second Nature.)