Noun
the domain ruled by an emperor or empress; the region over which imperial dominion is exercised
supreme authority; absolute dominion
Source: WordNetAccordingly, the king himself proposed to the Curiate Assembly a law granting him imperium, and the Curiate Assembly by voting in favor of the law would grant it. Source: Internet
After a term as Praetor, the magistrate would serve as a provincial governor in the office of Propraetor, wielding Propraetor imperium, commanding the province’s legions, and possessing ultimate authority within his province(s). Source: Internet
A consul was escorted by twelve lictors, owned imperium and wore the toga praetexta. Source: Internet
A dictator would have complete authority over civil and military matters within the Roman imperium, and was not legally responsible for his actions as a dictator and therefore was unquestionable. Source: Internet
After a theatrical display of refusal before the Senate, Augustus finally accepted authority over Rome's grain supply "by virtue of his proconsular imperium", and ended the crisis almost immediately. Source: Internet
Also, the laws that kept citizens safe from magistrates' misuse of imperium did not exist during the monarchical period. Source: Internet