The comment you responded to used "imperial", which is the adjective derived from empire. There's no other adjective for empire, and there's really no reason t

The comment you responded to used "imperial", which is the adjective derived from empire. There's no other adjective for empire, and there's really no reason to assume that use refers to modern meanings of imperialism (which is itself the noun derived from imperial...), meanings which are themselves derived from specific behaviours of recent empires.