commonwealth UK /ˈkɒmənˌwɛlθ/US /ˈkɑmənˌwɛlθ/ noun3 •The entirety of a (secular) society, a polity, a state.I'th' commonwealth I would by contraries Execute all things, for no kind of traffic Would I admit; no name of magistrate[…] — 1610 •Republic. Often capitalized, as Commonwealth. •(no longer used) The well-being of a community. formscommonwealths