Ning (寧) is the Mandarin word for "peaceful" or "tranquil" — used in many compound names (Ning'an, Anning).
Cao Ning is the Chinese pianist.
Ning does not currently appear in the US Social Security Administration's top 1,000 girls' names, so we don't publish a US rank or birth count for it. That says nothing about the name's standing elsewhere in the world — only that it sits outside the ranked US data we rely on.
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In Pythagorean numerology the letters of Ning reduce to 8, The Visionary. This is a traditional interpretive system, not a factual claim about the name.