"what we know in Latin as imperium"

Imperium roughly means ‘power.’ In ancient Rome, the term could be applied to the power or legal authority of the elected magistrates, the generals in the army, or later, the emperor. Imperium was the power to apply the law and make decisions within a particular area according to the extent of the magistracy. This authority could be overruled by those of a higher position, whose imperium outranked that of lower officials.