A sovereign or head of state: the highest public figure representing a nation (e.g., a monarch or a president).
国際会議には各国の元首が出席した。
Heads of state from various countries attended the international conference.
元首は憲法に基づいて職務を果たすべきだ。
The head of state should fulfill duties based on the constitution.
君主制の国では、元首は世襲で決まる場合が多い。
In monarchies, the head of state is often determined by heredity.