1. An alliance of nations joining together to fight a common enemy
   "The Allies fought against the Axis powers in World War II"

1. The alliance of nations that fought the Axis in World War II and which (with subsequent additions) signed the charter of the United Nations in 1945
    
2. In World War I the alliance of Great Britain and France and Russia and all the other nations that became allied with them in opposing the Central Powers

1. An associate who provides cooperation or assistance
   "he's a good ally in fight";
   - friend
    
2. A friendly nation
   "During the war, Britain and the United States were close allies"

1. Become an ally or associate, as by a treaty or marriage
   "He allied himself with the Communists"

Type of: affiliate, alignment, alinement [non-standard], alliance, associate, assort, body politic, coalition, commonwealth, consort, country, land, nation, res publica, state

Part of: alignment, alinement [non-standard], alliance, coalition

Encyclopedia: Allies, Mary