Irish Names & Surnames Explained

Traditional Irish Naming Patterns

Naming patterns are important when researching your family history. It has been a long standing custom in families around the world to name children after fathers, mothers, grandparents, important ancestors, relatives and friends. Middle names were often used for the preservation of a mother’s maiden name or the name of a prominent ancestor in that family. Names are very useful in tracking down lineages when there is little or no paper trail.

Names can give you clues to a person’s lineage, but other sources are still required in order to have genealogical proof. The Irish used a very particular naming pattern for children for children born beginning in the mid to late 1700s and through to the early to mid 1900s. It is important to note that not all Irish families followed the pattern although enough of them did that you can often use first names to learn more about an Irish ancestor’s unknown lineage. As with anything in genealogy, this should be proven with supporting documention, but Irish naming patterns are often helpful while building your family tree.

Traditional Irish Naming Pattern:

Naming Pattern Exceptions:

Naming patterns were sometimes affected by deaths in infancy. When a specific name was considered important within the family, the name would usually be given once again, to the next-born infant. In records, there are sometimes two or more children of the same name, baptized within the same family. Each baptism of this name, usually tells of the death of the older child of the same name.

Another example when the naming pattern is altered is when a child was stillborn, or very ill when born, or dying. Sadly, the child was baptized using a less-important family name, but the name of the paternal grandfather (or important ancestor) might be ‘reserved’ for a live birth, or for a child who was expected to live.

Surname Prefixes

Irish surnames of Gaelic origin were more common until Ireland fell under English rule. This led to the use of English versions of traditional Irish surnames. Many of these traditional names had prefixes:

“O”, “Fitz”, “Mc” and “Mac”

Mac or Mc – meaning “son of”

O – meaning “grandson of”

Fitz – meaning “son of” was sometimes substituted for the prefix ‘Mac’ or ‘Mc’ by many of the descendants of Anglo-Norman invaders.

For a period of time, English law in Ireland forbade the use of “O”, “Mc” and “Mac”, although “Fitz” was allowed. When researching your family name be aware that a name like Connor could have once been O’Connor.

The prefix O’ is unique to Ireland. It originates from the Gaelic word “ua,” meaning “grandson of.” Any name beginning with O’ is without question an Irish patronymic (from a male ancestor). The O’ surnames began in the 11th century in Ireland, before the Mc/Mac surnames. Examples of these surnames are O’Sullivan, O’Connor, O’Brien, and O’Leary.

Mc or Mac?

There is a myth about Scottish and Irish surnames that begin with the prefix Mac- or Mc-, that Mac- (as in MacDonald – son of Donald) designates a Scottish and Protestant heritage, where as Mc- (as in McCormick – son of Cormac) denotes an Irish Catholic family name. In fact there is no difference between these two prefixes. They may be either Irish or Scottish in origin and spelled different ways, with either prefix, even within the same family.

Mac- and Mc- both come from the Gaelic word “meic,” meaning “son of.”


In the early days of Irish settlement in Canada, such a large number of Irish names carried these prefixes that it became an ethnic slur for the Irish people to be called: “micks.”

Surnames that Describe the Profession of the Father

Some names beginning with Mc or Mac described the profession of the father.

MacMaster -“son of a master or religious leader”

Macpherson – “son of the parson,”

MacWard – “son of a poet or scribe,”

MacKenzie – “son of the fair one,”

MacDuff – “son of the dark one,”

McDowell – “son of the dark stranger.”.

Some families chose to conform to English laws, and some didn’t, which led to surname variations within the same family. Often Irish who emigrated dropped the prefixes when they arrived at their new countries of residence.

Top 200 Surnames in Ireland

Given Names and Meanings –


Given Names and Meanings


Researching Your Irish Roots

Don’t forget Nicknames

Most given names in Ireland have at least one associated nickname. When names are recorded in birth, marriage, and death, or in church records, a nickname may have been used instead of the given name (Kate for Catherine or Billy for William, for example). Many nicknames are easy to spot, but others are less well known. For example, the nicknames used for Bridget include Bedelia, Bess, Bessie, Biddy, Breda, Briddy, Bride, or Bridie.

Nicknames may also lead the researcher astray if incorrect assumptions are used. While some might assume that Anty is a nickname for Anthony (a male), it is, in fact, more likely a nickname for Anastasia (a female). Lou is both a nickname for male children named Aloysius, Lewis/Louis, and Ulysses as well as female children names Louise or Lucinda or Mary-Louise, or Mary-Lou.

In conclusion, while naming patterns weren’t always followed exactly (for example if there were only one or two children, the father’s relatives always took precedence in the naming of the children), they were usually followed closely.

Remember, if you have an Irish ancestor, and don’t know anything of their parentage, you can use naming patterns to help in your search.

Best of luck researching your Irish ancestry!


  • De Breffny, Brian. Guide on Irish Christian Names and their English equivalents. Article Christian Names in Ireland found for years 1670-1850. The Irish Ancestor, Vol.1 No. 1, pages 34-40.
  • Coghlan, Ronan. Irish First Names. Belfast, Ireland: Appletree Press, 1985.
  • Ó Corráin, Donnchadh, and Fidelma Maguire. Irish Names. 2nd ed. 1990. Reprint. Dublin, Ireland: The Lilliput Press, 1992.
  • MacLysaght, Edward. The Surnames of Ireland. 6th ed. Dublin, Ireland: Irish Academic Press, 1985.
  • Matheson, Sir Robert E. Special Report on Surnames in Ireland [Together with] Varieties and Synonyms of Surnames and Christian Names in Ireland. 1901. Reprint. Baltimore, Maryland: Genealogical Publishing Co., 1968.

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