noun
leader of an alliance; leading power
Refers to the dominant member of a coalition, alliance, or bloc, often in political, military, or economic contexts.
その軍事同盟では、アメリカが盟主の立場にある。
In that military alliance, the United States holds the position of leading power.
EUの盟主として、ドイツの役割は大きい。
As the leading power of the EU, Germany's role is significant.