Proper Nouns

Irish names have a rich history and a grammatical structure that changes depending on who is being referred to. First names are declined, and surnames change their form to indicate gender and marital status. This guide covers the main types of Irish names and how they are used.

Personal Names

First Names

Irish first names can be divided into two main groups: those of Gaelic origin and those from other languages.

Gaelic and Gaelicised Names

These names have deep roots in Irish history and mythology. Many were later adapted to sound like English names, even if they have different origins.

• Gaelic names: Tadhg, Niall, Eoghan, Domhnall, Brian, Conchubhar (or Connór), Diarmaid, Donncha, Cathal.
• Phonetic “translations”: Áine became Anne, Aoife became Eva, Tadhg became Timothy, and Eoghan became Eugene or Owen.

Many names from Norman and Christian traditions were also Gaelicised.

• Seán (from Jehan/Jean)
• Séamas (from James)
• Searlas (from Charles)
• Gearailt (from Gérard)
• Annraoi (from Henry)
• Micheál (from Michael)
• Sinéad (from Jeannette)
• Liam (from Guilliaume/William)
• Peadar (from Peter)
• Pól (from Paul)
• Eoin (from Johannes)

Declension of First Names

Male names often follow the first declension.

• Seán: genitive Sheáin, vocative a Sheáin
• Niall: genitive Néill, vocative a Néill
• Tomás: genitive Thomáis, vocative a Thomáis

Other declensions are also common.

• 3rd declension: Diarmaid (gen. Dhiarmada), Mathúin (gen. Mhathúna)
• 4th declension: Donncha (gen. Dhonncha)

Some names can be declined in more than one way. For example, Aonghus can be 3rd declension (gen. Aonghusa) or 1st declension (gen. Aonghuis).

Female first names mostly belong to the 2nd or 4th declension.

• Niamh (gen. Néimhe)
• Bríd (gen. Bhríde)
• Sinéad (gen. Shinéad)
• Síle (gen. Shíle)

Female names can be formed from male names using the diminutive suffix -ín, as in Póilín (from Pól). This suffix can also be used for male names, like Seáinín for “Johnny”.

If a person has multiple first names, historically the second name was put in the genitive and lenited, e.g., Seán Pheadair. Today, this is mainly seen in bynames that include a father’s or grandfather’s name.

English and Foreign Names

Names like Tom, Donald, John, and Janet are also common in Ireland. These names are typically not declined, lenited, or eclipsed. Many Irish people use both an English and an Irish version of their name, depending on the context.

Bynames

Bynames, or leasainmneacha, are used to provide more detail about a person.

• Adjectives: Adjectives like mór (big) and óg (young) function like “senior” and “junior”.
  • Séamas Óg Ó Néill - James O’Neill, Jr.
• Hair Colour: Adjectives describing hair colour are common.
  • Bríd Rua - Red-haired Bríd
  • Áine Bhán - Blonde Áine
• Patronymics: In the Gaeltacht, where a few surnames can be very common, people often use the names of their father and grandfather as bynames instead. These names are in the genitive and are lenited.
  • Seán Mhairtin Phóil - John, son of Martin, grandson of Paul.

Surnames

Irish surnames, or sloinnte, have distinct forms for men and women. They fall into several categories.

Gaelic and Gaelicised Surnames

This is the largest group, mostly comprising patronymic names beginning with Ó (descendant/grandson) or Mac (son).

Names with Ó and Mac

The prefixes Ó and Mac refer to a distant ancestor, not one’s immediate father or grandfather. These fixed surnames have been in use since the 11th and 12th centuries. Ó is more common, while Mac is found more frequently in the north of Ireland and is the standard in Scotland.

The name of the ancestor follows the prefix in the genitive case.

• Ó Braonáin (descendant of Braonán) - Anglicised as (O’)Brennan
• Ó Dónaill (descendant of Domhnall) - Anglicised as O’Donnell
• Mac Cárthaigh (son of Cárthach) - Anglicised as MacCarthy
• Mac Diarmada (son of Diarmaid) - Anglicised as MacDermot

Some names include the elements Maoil (follower, devotee) or Giolla (servant, youth), often followed by a saint’s name.

• Mac Giolla Phádraig (son of the servant of Patrick) - MacGilpatrick
• Ó Maoil Eoin (descendant of the follower of John) - O’Malone

The element Con- (from cú, dog/warrior) is part of the following name and is not lenited.

• Mac Conmara (son of the hound of the sea) - MacNamara

Some surnames derive from a profession or origin, often using Mac and the article an.

• Mac an Ghabhann (son of the smith) - MacGowan
• Mac an Bhaird (son of the bard) - Ward
• Mac an tSaoir (son of the craftsman) - MacAteer/McIntyre

The spelling of many surnames was updated during the spelling reform of the 1940s.

• Ó Seaghdha became Ó Sé
• Ó Murchadha became Ó Murchú
• Mac Mathghamhna became Mac Mathúna

Forms for Men

A man’s surname begins with Ó or Mac. Mag is a variant of Mac used before vowels and certain consonants.

• After Ó, a following vowel takes an h-prefix: Seán Ó hAonghusa.
• After Mac, the following name may be lenited, especially in younger names: Liam Mac Phaidín.
• In the genitive case, Ó becomes Uí and Mac becomes Mhic. Both cause lenition.
  • teach Sheáin Uí Mhurchú - Seán Murphy’s house
  • teach Thomáis Mhic Mhathúna - Thomas MacMahon’s house

Forms for Unmarried Women

For an unmarried woman, Ó is replaced by Ní (from Iníon Uí, daughter of the descendant) and Mac is replaced by Nic (from Iníon Mhic, daughter of the son). Both Ní and Nic cause lenition.

• Máire Ní Cheallaigh (Mary O’Kelly)
• Áine Nic Mhathúna (Ann MacMahon)

With some Mac- names, Ní is used instead of Nic, where the Mhic component is dropped entirely.

• Mairghréad Ní tSuibhne (Margret MacSweeny)

Forms for Married Women

When a woman takes her husband’s surname, the prefix Bean (woman/wife) is used. The husband’s surname is put into the genitive: Ó becomes Uí, and Mac becomes Mhic. The word Bean is often omitted in speech.

• Máire (Bean) Uí Cheallaigh (Mrs. Mary O’Kelly)
• Áine (Bean) Mhic Mhathúna (Mrs. Ann MacMahon)

A woman can also use a double-barrelled name, combining her maiden name and married name.

• Máire Nic Eochagáin Uí Chuinn - Máire Geoghegan-Quinn

The -(e)ach Form

Surnames with Ó and Mac can be turned into substantivised adjectives ending in -(e)ach. This form is always used with the definite article and without a first name. It is used to refer to someone by their surname alone, similar to saying “O’Neill” in English.

• Ó Néill → an Niallach
• Mac Cárthaigh → an Cárthach

This form is used in several contexts:

• Referring to a man: Tháinig an Niallach isteach. - O’Neill came in.
• Addressing a man (vocative): a Cheallaigh! - Mr. O’Kelly!
• For “Mrs.”: Bean an Cheallaigh - Mrs. O’Kelly.
• For a family (plural): na Ceallaigh - the O’Kellys.

Formal Titles and Family Names

Here is a summary of how to form common titles.

• Mr.: Use the -(e)ach form with the article (an Mathúnach) or Mac Uí (Mac Uí Mhathúna). For formal address, an tUasal is used: an tUasal Seán Ó Sé.
• Mrs.: Bean Uí (for Ó names) or Bean Mhic (for Mac names). Bean an + the genitive of the -(e)ach form is also used: Bean an Chadhnaigh.
• Miss: Iníon Uí or Iníon Mhic. The newer title “Ms.” can be translated as An Iníon Ní Cheallaigh.
• The … Family: Muintir + the ancestor’s name for Ó names (Muintir Cheallaigh). Clann Mhic for Mac names (Clann Mhic Mhathúna). The plural of the -(e)ach form is also common: na Ceallaigh.

Anglicised Forms

In English, Ó becomes O' and Mac is often shortened to Mc. These prefixes are attached without a space, and the following name is capitalised (e.g., O’Sullivan, MacCarthy). Over time, many families dropped the O' or Mac entirely (e.g., Kelly, Byrne).

Some names of Norman origin use Fitz- (from French fils, son) instead of Mac, as in FitzGerald (Mac Gearailt).

Surnames Ending in -(e)ach

A small number of common surnames are substantivised adjectives ending in -(e)ach and do not have an Ó or Mac form. They often indicate origin.

• Breathnach (Welsh) - Anglicised as Walsh, Wallace
• Caomhánach (follower of St. Caomhán) - Kavanagh
• Cinnseallach - Kinsella

For women, these surnames are lenited: Áine Bhreathnach. They are declined like first-declension nouns for male bearers.

Surnames with de

Surnames beginning with de are of Anglo-Norman origin, corresponding to the French de (from). It is not a sign of nobility.

• de Búrca - Burke
• de Buitléir - Butler
• de Paor - Power

The form is the same for men and women (Seán de Paor, Máire de Paor) and does not change in the genitive. These names can also form an -(e)ach version, such as an Búrcach for (Mr.) Burke.

Other Gaelicised Surnames

Many names of early Anglo-Norman, English, and Welsh settlers were Gaelicised without adding Ó, Mac, or de.

• Céitinn - Keating
• Daltún - Dalton
• Seoigh - Joyce

These names are generally not lenited after a first name. They can also form -(e)ach versions, like an Céitinneach for (Mr.) Keating.

Summary of Surname Forms

Here are examples showing the different forms for common surnames.

Ó Briain (O’Brian)

• Man: Seán Ó Briain
• Unmarried Woman: Síle Ní Bhriain
• Married Woman: Úna Uí Bhriain
• Mr. O’Brian: an Brianach
• The O’Brians: Muintir Bhriain or na Brianaigh

Mac Mathúna (MacMahon)

• Man: Seán Mac Mathúna
• Unmarried Woman: Síle Nic Mhathúna
• Married Woman: Úna Mhic Mhathúna
• Mr. MacMahon: an Mathúnach
• The MacMahons: Clann Mhic Mhathúna or na Mathúnaigh

Breathnach (Walsh)

• Man: Seán Breathnach
• Unmarried/Married Woman: Úna Bhreathnach
• Mr. Walsh: an Breathnach
• The Walshes: na Breathnaigh

de Búrca (Burke)

• Man: Seán de Búrca
• Unmarried/Married Woman: Úna de Búrca
• Mr. Burke: an Búrcach
• The Burkes: Muintir de Búrca or na Búrcaigh

Céitinn (Keating)

• Man: Seán Céitinn
• Unmarried/Married Woman: Úna Céitinn
• Mr. Keating: an Céitinneach
• The Keatings: Muintir Chéitinn or na Céitinnigh

Forms of Address

When addressing someone directly, Irish uses the vocative case, which is signalled by the particle a. This particle causes lenition.

• First names in the first declension change their ending: Seán becomes a Sheáin!.
• Surnames also change:
  • Ó becomes Uí: a Sheáin Uí Cheallaigh! (John O’Kelly!)
  • Mac becomes Mhic: a Phóil Mhic Mhathúna! (Paul MacMahon!)
  • -(e)ach becomes -(a)igh: a Phóil Bhreathnaigh! (Paul Walsh!)
  • Bean becomes Bhean: a Mháire Bhean Uí Cheallaigh! (Mrs. Mary O’Kelly!)

General forms of address are:

• Sir: a dhuine uasail!
• Madam: a bhean uasal!
• Ladies and Gentlemen: a dhaoine uaisle!

Place Names

Most places in Ireland have both an Irish and an English name. The Irish name is usually the original, with the English name often being a phonetic approximation. In Gaeltacht (Irish-speaking) areas, only the Irish names are official.

Irish place names are often descriptive, containing elements like cill (church), baile (town), cnoc (hill), and áth (ford).

The names of three provinces—Ulster (Ulaidh), Leinster (Laighin), and Connacht (Connachta)—are historically plural nouns, originally referring to the peoples of those regions. Munster (an Mhumhain) is a singular noun. Today, the province names are most often seen in the genitive case with the word Cúige (province), as in Cúige Uladh (Province of Ulster).

Many river and country names use the definite article, such as an Life (the Liffey), an Ghearmáin (Germany), and an Fhrainc (France). Exceptions include Éire (Ireland) and Sasana (England).