Noble lake or strong waterfall
A modern American invention likely created by combining the prefix 'Bri' (from Brianna or Bridget) with the popular suffix 'lynn'. It draws on the Celtic roots of Brianna, meaning 'noble' or 'strong', and the Welsh 'llyn', meaning 'lake'.
Less common today
Brilynn isn't in the latest US Top 1000. It last peaked at #2,256 in 2013.
US births per 5-year period, 1990βpresent (SSA data).