A commonwealth is a group of nations linked by history, or a state as a body. The Commonwealth games, the commonwealth of nations, a commonwealth of citizens.
The older meaning is the common good — the wealth here means wellbeing, not money — and that is what the word meant when England was briefly a commonwealth in the 1650s. Four American states call themselves one, which has no legal consequence.
1nouncommonwealthA group of nations linked by history.
“Many countries in the Commonwealth were once part of the British Empire.”
commonwealth is a political body.
Common plus wealth, in the old sense of wellbeing. It meant the common good before it meant a group of states.
From common + wealth. From c. 1450 as common wele (commonweal). In the form common-wealth (common welthe) from c. 1520, used by Tyndale in the sense "secular society" in particular, for which other authors preferred publike weal. Also from the 1520s treated as a synonym or loan-translation of res publica (republic) (Rollison 2017:67f).
Etymology from Wiktionary, CC BY-SA