The top 100 Irish last names explained

Find out more about your Irish roots and where your family name hails from

Mac Namara - Mac Conmara (hound of the sea). The most important sept of the Dál gCais after the O’Briens to whom they were marshals.

(O) Nolan - Knowlan Ó Nualláin (nuall, shout) In early times holding hereditary office under the Kings of Leinster, the chief of this sept was known as Prince of the Foherta, i.e. the Barony of Forth, in the present county of Carlow where the name was and still is numerous. A branch migrated to east Connacht and Co. Longford, in Roscommon and Mayo Nolan is used synonymously with Holohan (from the genitive plural); and in Fermanagh as an Anglicized form of ÓhUltacháin (Hultaghan). There was also a sept of the name of Corca Laoidhe which is now well represented in Co. Kerry.

Prendergast - de Priondragás. One of the powerful families which came to Ireland at the time of the Anglo-Norman invasion. They are still found mainly in the places of their original settlement. Some of those in Mayo assumed the name FitzMaurice.

MacQuaid - Quade  Mac Uaid (son of Wat). A well-known name in Co. Monaghan and adjacent areas. Without the prefix Mac the name is found in Co. Limerick.

(O) Rafferty - Ó Raithbheartaigh, mod. Ó Raifeartaigh. Though etymologically this (from rath bheartach, prosperity wielder) is distinct from Ó Robhartaigh (from robharta, full tide) anglicized O’Roarty, these two names have been treated as one, at least since the fifteenth century. As co-arbs of St. Columcille on Tory Island Roarty is now mainly Co. Donegal while Rafferty is of Co. Tyrone and Co. Lough.

(O) Rahilly - Ó Raithile this well-known Munster family originated as a branch of the Cenél Eoghain in Ulster buthas long been closely associated with west Munster, the poet Egan O’Rahilly for example was a Kerryman.

Redmond - Réamonn. A Hiberno-Norman family of importance throughout Irish history. They are associated almost entirely with South Wexford. The branch of the MacMurroughs in north of that county, some of whom adopted the name of Redmond whose chief was called Mac Davymore, are quite distinct from the MacRedmonds.

(O) Regan - Ó Riagain. Ó Réagainis used in county Waterford. There are three septs with this name. That shown as of Leix was in the early times one of the ‘Tribes of Tara’. The eponymous ancestors of the Thomond sept were akin to Brian Boru. The third was akin to the MacCarthys.

(O) Reilly - Ó Raghailligh One of the most numerous names in Ireland, especially so in Co. Cavan. The prefix O has been widely resumed in the anglicized form. The head of this important sept was chief Breffny O’Reilly

(O) Riordan - Rearden Ó Riordáin. This numerous sept belongs exclusively to Minster, he earlier form of Ó Rioghbhardáin reveals its derivation from riogh bhard, royal bard.

(O) Rooney - Ó Ruanaidh. Originating in Co. Down, where Ballyroney locates them, this name is now numerous in all the provinces except Munster. In West Ulster and north Connacht Rooney is often an abbreviation of Mulrooney.

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