imperium vs authorisation

imperium and authorisation both are nouns.

Word	Noun	Adjective	Verb	Adverb
imperium	Yes	No	No	No
authorisation	Yes	No	No	No

As nouns, authorisation is a hypernym of imperium; that is, authorisation is a word with a broader meaning than imperium:

Other hypernyms of imperium include authority, authorization, dominance, potency, say-so.

imperium (noun)	authorisation (noun)
supreme authority; absolute dominion	the act of conferring legality or sanction or formal warrant
the domain ruled by an emperor or empress; the region over which imperial dominion is exercised	the power or right to give orders or make decisions
	official permission or approval
	a document giving an official instruction or command