Caitlin (Irish pronunciation: [ˈkatʲlʲiːnʲ]) is a feminine given name of Irish origin. Historically, the Irish name Caitlín was anglicized as Cathleen or Kathleen. In the 1970s, however, non-Irish speakers began pronouncing the name according to English spelling rules as KAYT-lin, which led to many variations in spelling such as Caitlin, Ceitlin, Catelynn, Caitlyn, Katlyn, Kaitlin, Kaitlyn, Katelyn and Katelynn.
It is the Irish version of the Old French name Cateline [katlin], which comes from Catherine, which in turn comes from the Ancient Greek Αἰκατερίνη (Aikaterine). Catherine is attributed to St. Catherine of Alexandria. Along with the many other variants of Catherine, it is generally believed to mean "pure" because of its long association with the Greek adjective καθαρός katharos (pure), though the name did not evolve from this word.