REALM
A realm is a community or territory over which a sovereign rules.
The term is commonly used to describe a monarchical or dynastic state.
A realm may also be a subdivision within an empire,[1] if it has its own monarch, e.g. the German Empire.
The Old French word reaume, modern French royaume, was the word first adopted in English; the fixed modern spelling does not appear until the beginning of the 17th century.
The word supposedly derives from medieval Latin regalimen, from regalis, of or belonging to a rex (king).[2]
The word rex itself is derived from the Latin verb regere, which means "to rule".
Thus the literal meaning of the word realm is "the territory of a ruler", traditionally a monarch (emperor, king, grand duke, prince, etc.).