Noble kind
Addalynn is a modern American elaboration of Adeline or Adelaide. It combines the Germanic root 'adal', meaning noble, with the popular 'lynn' suffix, which often refers to a lake or pool in Welsh and English contexts.
Less common today
Addalynn isn't in the latest US Top 1000. It last peaked at #1,160 in 2015.
US births per 5-year period, 1990βpresent (SSA data).