definition of imperial
adjective. The definition of imperial is something magnificent, domineering or related to an empire. 1  A royal government with control over an empire is an example of an imperial government.2  A person with a domineering and controlling manner is an example of someone who would be described as having an imperial personality.he definition of imperial is something magnificent, domineering or related to an empire. 1  A royal government with control over an empire is an example of an imperial government. 2  A person with a domineering and controlling manner is an example of someone who would be described as having an imperial personality.