a friendly nation
"During the war, our country relied heavily on its ally to provide essential supplies and military support."
A person, group, or state (etc) which is associated with another for a common cause; one united to another by treaty or common purpose; a confederate.
"The old-fashioned term ally is sometimes used as an alternative spelling for a glass marble or taw."
Alternative form of alley (a glass marble or taw)
In plain English: An ally is someone who supports and works with another person toward a common goal even if they are not part of that same group.
"We need to find an ally in this difficult situation."
become an ally or associate, as by a treaty or marriage
"He allied himself with the Communists"
To unite, or form a connection between, as between families by marriage, or between princes and states by treaty, league, or confederacy.
"The two neighboring kingdoms decided to ally against the common enemy through a formal treaty of mutual defense."
In plain English: To ally with someone means to join forces and work together toward a common goal.
"The two countries decided to ally against their common enemy."
Usage: Use "ally" when describing two parties joining forces for a shared goal through treaties or common purpose rather than simple friendship. This verb specifically implies a formal agreement to support each other against an opponent or in pursuit of mutual interests.
A diminutive of the female given names Alice, Alison, Alexandra, or other names beginning with Al-[[]], from the Germanic languages or Ancient Greek
"Her teachers affectionately called her Ally because it was a short form of her full name, Alexandria."
The word ally comes from the Anglo-Norman verb alier, which originally meant "to join together" or "unite." Over time, this sense of joining evolved in English to specifically refer to forming a political alliance.