The Irish surname Noonan or O’Noonan is of patronymic origin and is very numerous: mainly Munster and South East. The name Noonan in Gaelic, Ó Nuanáin, a corruption of Ó h-Ionmhaineáin from ionmhain, meaning “dear or beloved”. A sept or clan of North County Cork, now numerous in county Limerick. A notable bearer of the name is Michael Noonan the noted Irish politician. Today there are over 12,500 people with the family name Noonan living in The United States.