1. uncountable noun
Dominion is control or authority. [formal] [+ over] ⇒ They truly believe they have dominion over us.
2. countable noun [oft with poss]
A dominion is an area of land that is controlled by a ruler. [+ of] ⇒ The Republic is a dominion of the Brazilian people.
3. countable noun The Dominions were the nations which in the past were part of the British Empire but which had their own government.
COBUILD Advanced English Dictionary. Copyright © Harper Collins Publishers