Slender, fair, or a modern combination of Kay and Lynn
Keilynn is a modern American invention, likely created by blending the prefix 'Kei' (from names like Keira or Kay) with the popular suffix 'lynn'. It may also be interpreted as a variant of the Irish name Caoilinn, which means slender and fair. As a contemporary coinage, its meaning is often defined by the elements chosen by the parents.
Less common today
Keilynn isn't in the latest US Top 1000. It last peaked at #9,709 in 2010.
US births per 5-year period, 1990βpresent (SSA data).