The word in question is pharmakos (wizard, magician, poisoner), a synonym of pharmakeus (which Plato uses), but with the unique feature of having been overdetermined, overlaid by Greek culture with another function. Another role and a formidable one.
The character of the pharmakos has been compared to a scapegoat. The evil and the outside, the expulsion of the evil, its exclusion out of the body and out of the city.
- Jacques Derrida in Dissemination