The Irish surname Looney is an anglicized form of the Gaelic name Ó Luanaigh meaning “descendant of Luanach,’ a personal name derived from luanmeaning “warrior.” There were originally two septs in Ireland, one belonging to the Munster counties of Cork, Kerry and Clare, and the other as Loonan, and Lunan, to County Waterford, and also County Donegal. Lowney, a form of Looney is popular in the Castletownbere region of West Cork. The second sept of O' Luanaigh were important in medieval times. They were once chiefs of Cenel Moen in the barony of Raphoe, County Donegal. The territory of Manterlooney in County Tyrone is named after this sept.