allies (Noun) — An alliance of nations joining together to fight a common enemy.
allies (Noun) — 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.
allies (Noun) — 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.
allies (Noun) — A friendly nation.
allies (Noun) — An associate who provides cooperation or assistance. ex. "he's a good ally in fight"
allies (Verb) — Become an ally or associate, as by a treaty or marriage. ex. "He allied himself with the Communists"