Excommunicate Traitoris is a High Gothic bureaucratic designation of the Administratum and the Inquisition that represents the highest form of Imperial reproach against an Imperial citizen or organisation that has committed extreme acts of heresy against the Emperor of Mankind, including mutation, apostasy, blasphemy, rebellion and corruption by Chaos.
With no sanctuary to be found within the realms of Man, they will be forever hunted for the rest of their days or executed on sight by any and all loyal servants of the Imperium.