COMMONWEALTH, a term generally synonymous with commonweal, i.e. public welfare, but more particularly signifying a form of government in which the general public have a direct voice. "The Commonwealth" is used in a special sense to denote the period in English history between the execution of Charles I. in 1649 and the Restoration in 1660. Commonwealth is also the official designation in America of the states of Massachusetts, Pennsylvania, Virginia and Kentucky. The Commonwealth of Australia is the title of the federation of Australian colonies carried out in 1900.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)