Commonwealth

Commonwealth noun

1. [the] (also British Commonwealth especially old use, Commonwealth of Nations formal) an organization of about 50 independent countries, most of which were formerly part of the British Empire, established in order to encourage trade and friendly relations among its members. The British king or queen is the head of the Commonwealth, and there is a meeting each year for all its heads of government.

2 [countableC] the official title of

a) some states of the US, for example Virginia and Kentucky,

b) some countries that are officially connected with the US, especially Puerto Rico

c) some countries made up of a group of states, such as Australia

3. the Commonwealth England during the period 1649–60, when there was no king or queen and the country was ruled by Oliver Cromwell.

From Longman Business Dictionary

CommonwealthCom·mon·wealth /ˈkɒmənwelθˈkɑː-/ (also Commonwealth of Nations) nounORGANIZATIONS

an organization of about 50 countries that were once part of the British EMPIRE, and that are now connected politically and economically

Britain’s gradual conversion of the colonial Empire into the British Commonwealth of Nations