But this is inherently a false statement. We already use definitions for concepts and imaginary entities, because we obviously need differentiation standards to describe what we are talking about. E.g. vampires and dragons don't exist but have their own definition, so that people understand two different kinds of concepts. If you "stretch" the vampire definition to resemble a dragon, it will become a dragon. If you create a new imaginary entity you will unavoidably attribute it with certain characteristics. Communication would literally not be possible if you don't define concepts, whether they are imaginary or not.
My point was that what defines zombies as an entity has some unique core characteristics. If it didn't, the "zombie" would never have become a thing and there wouldn't be a definition for it in the first place. And these characteristics are common knowledge in horror studies and have been researched by actual psychologists already, and as I pointed out earlier, they extend further than appearance. So every time this is being discussed, I am like "wtf" for a good reason.