Translation guide
A territory ruled by a prince or princess; the rank or office of a prince.
The learner wants to refer to a principality as a political or geographical entity, such as Monaco or historical principalities.
Standard term for a principality as a sovereign state or territory ruled by a prince. Used for modern examples like Monaco (モナコ公国) and historical ones.
Also means principality, but specifically for a territory ruled by a marquis or prince of lower rank. Less common than 公国 and often historical.
The learner wants to refer to the abstract status, dignity, or position of being a prince, not the territory.
Means 'the rank/position of a prince'. A natural way to express the abstract concept.
彼は公の地位に就いた。
He assumed the rank of a prince.
The English word 'principality' is sometimes confused with 'principle'. In Japanese, 'principle' is 原理 (げんり) or 原則 (げんそく). Make sure the context is about a prince's domain or rank.
モナコは小さな公国です。
Monaco is a small principality.
中世ヨーロッパには多くの公国があった。
There were many principalities in medieval Europe.
That principality was part of the Holy Roman Empire.
Specifically 'the rank of a duke', but can be used when principality refers to a prince's title in a broader sense. Note: 公爵 is duke, not prince, but in some contexts principality may be rendered this way.
その公爵の位は世襲だった。
The principality was hereditary.