Noonan, ó hIonmhaineáin, ó Nuanáin A Gaelic surname derived from Ionmhain meaning ‘beloved’. An ecclesiastical sept who were erenaghs of the church of St. Beretchert at Tullylease, in the Barony of Duhallow in Cork. In 1890 Noonan was principally found in Cork, Clare, Limerick and Tipperary, and the estimated number of bearers was 3,720 (including variants). In the United States Noonan is the 3,158th most numerous surname with an estimated 11,000 bearers.