Adelynn is the modern American double-N spelling of Adeline — from the Old Germanic adal ("noble"). A top-500 US baby name since 2010.
Adelynn 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 Adelynn reduce to 3, The Communicator. This is a traditional interpretive system, not a factual claim about the name.