Ninlil (𒀭𒊩𒌆𒆤) was the Sumerian goddess of the air — wife of Enlil, the chief Sumerian god. Her name means "lady of the wind" (nin = lady, lil = wind).
Ninlil is rare but distinctive.
Ninlil 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.
In Pythagorean numerology the letters of Ninlil reduce to 7, The Seeker. This is a traditional interpretive system, not a factual claim about the name.