Your Ancestor's Surname

The surname (last name) recorded on American records was written and spelled by American clerks who may not have understood your ancestor's pronunciation of his name. In Ireland, the surname may be recorded quite differently. For example, the surname Thompson may be recorded in Ireland as MacComb (meaning son of Thomas). The best source for locating the origin and meaning of surnames, surname variants, surname distribution maps, and more is John Gresham's Irish Surnames. This massive work is on compact disc. There are also has a good number of books that can help you find more information on Irish surnames and given names (first names). See especially

MacLysaght, Edward, Irish Families: Their Names, Arms and Origins

MacLysaght, Edward, More Irish Families

MacLysaght, Edwad, The Surnames of Ireland