This is a given name derived from the Irish surname “Ó Raghallaigh or the Anglicised form O'Reilly”. The origin of this name is still today quite uncertain. The theories include: 1) The name is composed of two elements: from the Gaelic “ràgh” (Irish: Rás; Proto-Germanic: *rēsō), meaning “race” plus the Irish and Scottish Gaelic “Caillech”, meaning “veiled one”, an adjectival form of “caille”, meaning “veil”. In Gaelic mythology, Cailleach is a divine hag, a creator deity and weather deity, and possibly an ancestor deity. 2) From an Old English surname and place name, from the root “roggo lēah”, meaning "rye clearing" (rye, type of grain). The Ó Raghallaigh family were part of the Connachta, with the eponymous Raghallach said to have died at the Battle of Clontarf in 1014. The family became the kings of East Breifne, modern-day County Cavan and County Longford.