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"

Derived forms: allies, allying, allied

Type of: affiliate, associate, assort, body politic, commonwealth, consort, country, land, nation, res publica, state

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

Encyclopedia: Ally, Haute-Loire