Kathleen is the English form of the Irish Caitlín, which in turn comes from Katherine and is usually explained as "pure", from the Greek katharos. It was one of the great Irish American names of the 20th century and a top 20 choice in the 1940s and 1950s. Kathleen still ranked number 204 in 2000, left the top 1000 for good in 2022 and stands at number 1156 in 2025.