Meaning of REALM in English

(COUNTRY) [noun] [C] [formal or literary] - a country ruled by a king or queena peer/knight of the realmcoins of the realmthe defence of the realmThe matter was hotly debated in all the towns of the realm.In a realm as large as medieval Germany, the king faced a huge task.

Cambridge English vocab.      Кембриджский английский словарь.