Irish Surnames of Gaelic Origin

Gaelic Surnames in Ireland

These are the oldest names in Ireland and often reflect the clan and territorial system that prevailed in the Celtic era. Gaelic names fall into four broad groups:

1. Names referencing an ancestor

Examples include O Toole (Ó Tuathail) meaning "descendents of Tuathal", who was a 10th century King of Leinster. It is not always a specific known character, so while MacCormack (MacCormac) means "son of Cormac", there is no single Cormac to whom all can trace their ancestry.

2. Names deriving from a place

McNulty (Mac An Ultaigh) which means "Son of Ulster" or Delaney (Ó Dubhshlaine) meaning "of the black river Slaney". Conversely a huge number of Irish place names are derived from the names of people who lived in or ruled over them.

3. Names relating to work or a profession

O Leary (O Laoghaire) which means "descendant of the calf keeper" or Guinness (MacAonghusa) meaning "son of the healer"

4. Names based on personal characteristics

Reilly (Ó Raghailligh) means "of the gregarious people" while, a little unkindly perhaps, Kennedy (Ó Cinneide) which means "of the ugly head".

There are a few oddities which fall outside these categories, but the vast majority lie in one or other of those four categories.

Sons and Grandsons

The commonly found "Mc", which is the same as "Mac", and "O" before an Irish name mean, respectively "Son of" and "grandson of".

So MacAuley means "son of Auley", and O Keefe (O Caoinmh) means "grandson of Caoinmh". Essentially both can be taken to mean "descendent of".

The name is not always related to a named person, so that O'Grady (Ó Grádaigh) means "descendent of the illustrious", McGill (Mac An Ghaill) "descendent of the foreigner" and, interestingly, MacTaggart (Mac antSagart) means "son of the priest".

It is often erroneously said the Mc indicates Irish origin and Mac Scottish origin. In fact there is no difference at all.

The languages of both countries are similar and the two are effectively interchangeable and say nothing whatever about origin.

Daughters and Wives

Obviously daughters cannot be "son of" or "grandson of" and so female members of a family will have before their names "Ní" or "Níc", which is derived from from Iníon Mhic meaning "daughter of the son of".

For example my name in Irish is Cait Ní Nuaillain (Katherine Nolan), but my brother is Seamus Ó Nuaillain (James Nolan).

Things became even more complicated when marriages occur.

A wife is not the "son of" anyone, least of all her husbands father! So, if Mary marries Sean Ó Doinn, she become Mary Bean Uí Doinn, which literally means "wife of the grandson of". Had she married Sean MacCarthaigh she would have been Mary Bean MhicCarthaigh or "wife of the son of".

In most case the "bean" or "wife" part is not commonly used, so she would be known as Mary Uí Doinn or Mary MhicCarthaigh, but her married status would still be quite clear from her name.

The Anglicisation of Gaelic Names

During the 18th and 19th centuries there were concerted efforts by the English to suppress the use of the Irish Language and the use of Irish names.

At this time the use of Mac and O was dropped by many families, often a pragmatic move which improved their chances of social and economic advancement. Some families have since revived the O or Mac, others never did, which explains why you will find Mahony and O'Mahony, Neill and O'Neill, all with a common history.

Others adopted anglicised versions of old Gaelic names and there can be a multitude of different English versions of the same name. Sometimes the Anglicised version is a translation, sometime a phonetic spelling of the Irish.

Take the very similar Irish names MacAodha and MacAoda, both of which mean "son of Aodh" or "son of Hugh", since Aodh is the Irish version of the given name Hugh.

Depending on where in Ireland you live, Aodh will be pronounced "ee" as in the word 'see' or "ay", as in the word 'say'.

The following are all Anglicised versions of either of these names: Magee, MacKee, McKee, MacCoy, McKee, Hughes, MacKay, McHugh, Hayes, Hewson.

The last name there may be familiar - Bono of Irish band U2 is properly known as Paul Hewson, and in Irish would be known as Pól MacAoda.

Distribution of Gaelic Names

Most names of Gaelic origin are widely distributed in Ireland, and indeed elsewhere, but it is amazing how closely some have stuck to the places where their names originated often more than a thousand years ago.

For example the name Moriarty is very rarely found outside of Co Kerry and if you meet a Riordan you can be fairly sure he will speak with the distinctive accent of Co Cork. Both names are still common in their home areas but rare elsewhere.

Even with very frequently occuring names, such as Brennan, which is pretty much ubiquitous, concentrations in small areas occur.

There is a large concentration of Brennans in Donegal, among them the well known Irish singer Enya (left), whose real name is Eithne Ní Bhraonain.

There are so many families with the surname Brennan around the town of Castlecomer in Co Kilkenny that nicknames are used to distinguish them, so that you have Brennan Con, Brennan Duff or Brennan Joes. These are sometimes even included when addressing post!

The story of the Castlecomer Brennans shows how families can persist in an area againt all the odds. That the Brennans have survived there at all, let alone thrived, is remarkable.

Prior to the 12th century they were the dominant clan in what is now the Kilkenny City area, effective rulers of vast areas of land. When the Normans arrived they lost almost all their lands and were driven to the less fertile area around Castlecomer.

In the 17th century they lost the land they had there to the English Wandesfordes who were granted their land by the Crown, relegating the Brennans to the status of tenent farmers. But through all that they survived and remain very numerous in their home territory today, where they once again own the land they farm. Quite a story of dogged determination.

Scots Gaelic Names

The Mac's of Ireland and Scotland are not entirely unrelated and as waves of Scottish planters came to Ireland they brought their names with them.

It can sometime be tricky to decide whether a name is of Irish or Scots Gaelic origin, but there is a good hint in the religion of its bearer. Those with Gaelic Irish names are predominantly Catholic, those whose names originated in Scotland mainly protestant.

Scottish names are by far more common in the Northern counties than in any other part of Ireland, in fact they are rare elsewhere.

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