Caitlyn is an American spelling of the Irish Caitlín, which is the Gaelic form of Catherine and so goes back to the Greek katharos, "pure". The Irish pronunciation is closer to Kathleen, but American parents read the name as Kate-lin, and spellings like Kaitlyn and Katelyn flourished in the 1990s. Caitlyn stood at number 118 in 2000, left the top 1000 after 2015 and ranks number 2492 among girls' names in 2025.