From Ecclesiastical Latin Kyrie, contraction of the Ancient Greek phrase Κύριε ἐλέησον (Kúrie eléēson, “Lord, have mercy”), from Ancient Greek Κύριε (Kúrie), vocative form of Κύριος (Kúrios, “Lord”), from κῦρος (kûros, “supremacy, authority”), from Proto-Indo-European *ḱēw-, *ḱewh₁- (“to swell, spread out, be strong, prevail”).