2. countable noun
Commonwealth is used in the official names of some countries, groups of countries, or parts of
...the Commonwealth of Australia.
...the Commonwealth of Independent States, which replaced the Soviet Union.
3. singular noun
If you refer
to a commonwealth of
nations, you are referring to a group of countries who are friendly
towards each other and have something in common.
...a commonwealth of nations without economic borders.
COBUILD Advanced English Dictionary. Copyright © HarperCollins Publishers