Commonwealth, body of people in a politically organized community that is independent or semi-independent, and in which the government functions by the common consent of the people. The United States and its separate, semiautonomous states are thus commonwealths, although only four states—Kentucky, Massachusetts, Pennsylvania, and Virginia—have officially designated themselves as such. The term commonwealth is also sometimes used as a synonym for commonweal, or “general welfare.” In addition it is applied in a general sense to an association of persons having a common interest, as of art, literature, or learning, and to the uniting interest itself, as, for instance, the commonwealth of learning.

In English history, the Commonwealth was the government established by Parliament and headed by the English soldier Oliver Cromwell after the execution of King Charles I in 1649 and continuing until the Restoration in 1660. The term is also applied specifically, and officially, to Australia and the Bahamas and to the association of countries known as the Commonwealth of Nations.