coalition - partnership - union - association - league - confederation - federation - consortium - pact - treaty - accord - affiliation - collaboration - cooperation merger - syndicate - bloc - entente compact - fellowship - fraternity - guild - network - organization - society - brotherhood - sisterhood - connection - link - tie - bond - relationship - alignment - combination - amalgamation - integration - unification - solidarity - concord - understanding - agreement
An alliance is a formal agreement or treaty between two or more nations or groups to cooperate for specific purposes, such as mutual defense or economic benefit. Alliances can be political, military, or economic in nature and are formed to strengthen the members against common threats or to achieve shared objectives. Historical examples include NATO, the European Union, and various wartime coalitions. Alliances can provide strategic advantages but also require trust and sustained cooperation among the members.