An ally is someone who is united with another person or group in a common purpose, often for mutual support and protection. In the context of NATO, an ally refers to any member country that is part of the alliance and has committed to collective defense with the other member countries.
Note: The provided meaning of the answer is for the latest New York Times crossword puzzle clue: Any member of NATO, to another. Explanations are generated by AI and may be inaccurate.