Kailynn is a modern American blend of Kay and Lynn and a sister spelling of Kaylin and Kaelyn. Kay is a short form of Katherine, usually read as "pure", while Lynn goes back to the Welsh llyn, "lake". The double-n spelling entered the US top 1000 just once, at number 899 in 2011, and has faded since, from number 1128 in 2015 to number 2343 in 2025.