Irish surnames may be Gaelic, Anglo-Norman, English, Scottish, Welsh, or derived from several traditions at once. Anglicization changed many spellings, so the modern form is only one clue.
Irish surnames in Family Research
Ó and Mac
Ó, earlier Ua, originally meant “grandson” and came to mean “descendant of.” Mac means “son.” Ní is used in a woman’s surname as a reduced form associated with “daughter of,” with grammatical changes to the following name. These elements became hereditary, so a modern O’Brien is not literally “Brian’s son” or “Brian Jr.”
Ó Cléirigh, anglicized as O’Clery, O’Cleary, Clery, or Cleary, means “descendant of Cléireach,” a personal name related to “cleric” or “clerk.” The family is recorded very early and became famous for scholars who helped compile the Annals of the Four Masters. Popular accounts sometimes call it the first hereditary surname in Europe or assign an exact first date, but those claims depend on how “hereditary surname” is defined and should be presented cautiously.
Fitz
Fitz comes from Anglo-Norman fiz, “son,” corresponding to modern French fils. It appears in Norman names such as Fitzgerald. Fitzpatrick has a different history in many Irish lines: it is an anglicized form of the Gaelic Mac Giolla Phádraig, “son of the servant of Patrick.” The prefix alone therefore does not establish Norman ancestry.
Occupational and Descriptive Names
Baker, Cooper, Fisher, Butler, Thatcher, Mason, Smith, and Wright are occupational surnames found in Ireland, but most are English-language formations and may have arrived with settlers or developed in more than one place. Their presence in an Irish family does not make the word itself Gaelic.
Bray, Hill, River or Rivers, Montgomery, Mondale, and similar names may be locative, topographic, or imported. Mondale should not be translated mechanically as “dale,” and it is not a dependable example of a Gaelic Irish surname. Walsh or Welsh originally identified a Welsh or Brittonic person in some contexts. Each name needs its own place and record history; a familiar English meaning is not enough.
Gaelic Names in English Forms
Ó Ceallaigh became Kelly and Kelley. It means “descendant of Ceallach,” but the meaning of the personal name Ceallach is debated. Ó Murchadha became Murphy and means “descendant of Murchadh,” a personal name whose elements relate to sea and battle. Mac Gabhann means “son of the smith” and often became McGowan, MacGowan, or, in some lines, Smith. McAllen may represent a form of Mac Ailín or Mac Aileáin, “son of Ailín or Alan,” in some lines; the popular translation of Allen as “handsome” is not certain enough to define every family. An English form can represent more than one Gaelic original, so researchers should not translate backward without supporting records.
Start with the most recent known Irish record and work toward a specific townland, parish, and county. Search the modern spelling, Gaelic form, common anglicizations, and phonetic variants. The prefix can suggest a naming tradition, but the records—not the prefix—establish the family line.
Learn More
Continue with Understanding The Meaning of Your American Surname, or explore our free genealogy eBooks. For further research, see Irish-language surname database.
