leader of an alliance; leading power
Refers to the dominant member of a coalition, alliance, or bloc, often in political, military, or economic contexts.
In that military alliance, the United States holds the position of leading power.
As the leading power of the EU, Germany's role is significant.
That country became the leading power of the regional economic bloc.
They have maintained their position as the leading power for many years.
The small countries looked up to the great power as their leader.
宗主 (suzerain) denotes historical or ceremonial overlordship over vassals, while 盟主 denotes the dominant member of a modern alliance or bloc.
盟友 means a close ally or comrade (an equal partner), while 盟主 means the leader who heads the alliance.
Compound of 盟 (alliance) and 主 (master, leader). The reading めいしゅ is the standard on'yomi combination.