
If You're A Wee Bit Irish published by The Irish Family Names Society, La Mesa, CA, 1978 list a chart of family relationships collected from folk tradition. A new guide to kings, queens and commoners.
The children of John Francis Nunan have always placed great significance in the spelling of their name. It has been generally believed that the spelling NUnan is distinct and separate from NOOnan. Research has shown that is not the case; the spelling of many Irish names is variable and dependent on the way the owner or government officials believed it should be written. In the Okief, Coshe Mang, Slieve Lougher and Upper Blackwater In Ireland by Albert Eugene Casey, M.D. mentions one account of a family named Nunan with a niece making reference to the death of her aunt named Noonan. Edward MacLysaght is the acknowledged expert on the origins of Irish family names. In his book Irish Families on page 245 the following appears:
O'Nunan, Noonan
The name Noonan, which is also, but less frequently, spelt Nunan (the prefix O has not been resumed), belongs almost exclusively to the province of Munster and particularly to County Cork, where it originated. In modern Irish it is O'Nuanain: this is a corrupt or contracted form of the older O'h-Ionmhaineain, of which the anglicized form O'Hinunane, now obsolete, is approximately a phonetic rendering. In early time O'Noonan was chief of a sept (clan or tribe) in Duhallow and the O'Noonans were also connected with the Church as erenaghs (hereditary custodians) of the church of St. Beretchert at Tullylease in the barony of Duhallow.
The most notable man of the name in modern times was James Patrick Noonan, (1878-1929), American labor leader, son of an Irish emigrant. In the middle ages William O'Noonan, alias Ouhynaunan, was remarkable inasmuch as at a time when the native Irish were officially outlaws in English law, he was "the King's surgeon" and in 1341 he cured Lionel Duke of Clarence, son of King Edward III, the Viceroy of Ireland.
Other spellings of Nunan include, Newnan, Neenan, Nonan, Nonen, Noonen, Noonin, Noonon, and Noonane. MacLysaght also lists O'Naoidheanian (naoidhean, child), a west Clare name often changed to Noonan.
If You're A Wee Bit Irish lists 800 Gaelic Irish Families (before 1600). O'Nunan is listed as one of the families descended from CORMAC CASS who lived in 250 AD, the son of OILILL OLOM, "The Wise", and ancestor of the collective family called the Dal Cais. In fact, the custom among the early Christian Irish and many other Europeans was to trace their family beginnings back to Adam. This book includes the Nunans as descendants of Adam.