alliance

league, federation, union, alliance

这些名词均含“联盟、同盟、联合会”之意。
league: 普通用词，指为了共同的利益而建立的地区性、全国性或国际性的联合组织，也指民间或半官方组织的联盟。
federation: 泛指用条款固定下来的一切联合，尤指联邦政府。
union: 普通用词，指由若干个体结成的一个统一的整体。强调其永久性。
alliance: 普通用词，指对双方均有利的任何联盟。

名词 alliance:

1. the state of being allied or confederated
   同义词：confederation
2. a connection based on kinship or marriage or common interest
   同义词：bond
3. an organization of people (or countries) involved in a pact or treaty
   同义词：coalition, alignment, alinement
4. a formal agreement establishing an association or alliance between nations or other groups to achieve a particular aim
5. the act of forming an alliance or confederation
   同义词：confederation

1. The alliance had been forged in the crucible of war.
   这个联盟经受了战争的严峻考验。
2. They broke up the alliance.
   他们中止了联盟。
3. Which country is the predominant member of the alliance?
   哪个国家在联盟中居于支配地位？
4. They made an alliance against the common enemy.
   他们联合起来抵御共同的敌人。