盟主的英文：
the leader of an alliance

参考例句：

Yuan Shao, the leader of an opposition force, led a punitive expedition to Lüoyang, the capital.
各诸侯，举袁绍为盟主，带各路兵马杀向洛阳，讨伐董贼。

leader是什么意思：
n. 领导者；指挥；领唱；首席小提琴手；负责人；领先者；佼佼者

Then you select the leader.
然后你们选出指挥。

The two leaders are struggling for power.
那两个领导人正在争夺权力。

The leaders of the interest will help you.
业内的领导们将帮助你。

They were intriguing to spring their leader.
他们正密谋把头儿救出来。

The leaders will not agree to the course of the dean.
领导们不会赞同主任的做法。

alliance是什么意思：
n. 结盟；联盟

It was an uneasy alliance.
那是一个不稳定的联盟。

They are in alliance with each other.
他们结成了联盟。

Which country is the predominant member of the alliance ?
哪个国家在联盟中居於支配地位?

They joined with a ramshackle alliance of other rebels.
他们和一个由其他反叛者草草拼凑成的同盟联起手来。

I had coached the Alliance team for some time.
我曾在联盟队担任过一段时间的教练。