Modern spelling variant of Caitlin, the Irish form of Catherine, from Greek 'katharos' meaning 'pure.'
Caitilyn is a modern spelling variant of Caitlin, the Irish form of Catherine, ultimately from Greek katharos, meaning pure. Catherine has traveled widely through European languages for centuries, and Caitlin became one of the best-known Irish-derived forms in English.
Caitilyn takes that familiar modern Irish shape and gives it an ornamental spelling that feels current and individualized. Because the name is built from an established classic, Caitilyn inherits a long history of feminine use even though the spelling itself is new. The extra letters give it a softer visual texture and a more decorative appearance, which is often part of the appeal of contemporary variants.
Caitilyn sounds youthful, bright, and lightly stylized, with enough connection to Caitlin to remain recognizable. It is a good example of how older names continue to evolve in English through spelling creativity rather than wholesale reinvention.