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The Origin of Irish Family Names

It is a help when tracing your family history to know something about the origin of and evolution of Irish names and particularly how names have changed over the centuries.

Early times: In ancient Ireland the population was much smaller than today and the mass movement of people was uncommon. It was usual therefore for a person to be known only by one name: Niall, Eoin, Art, etc. Once there was no one else in the locality with the same name then this was not a problem.

The Gaelic Clann system was well established and this gave people a common identity with their people of the tribe and with the commonly shared area. This single name system began to break down during the eleventh century as the population was growing and there was a need for a further means of identification. The solution was to adopt a prefix such as Mac (Mc is an abreviation) or Ó. Mac means 'son of' whilst Ó means 'grandson of'. Mac surnames are generally of a much later date than Ó. The vast majority of Gaelic Irish surnames were created during the eleventh and twelfth centuries.

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It should be noted that the Scottish Gaels were actually descendants of Gaelic emigrants to Scotland. The word 'Scotus' is Latin for 'Irishman'. Scottish settlers who moved to Ireland (and especially Ulster) may already have been of Gaelic Irish descent.

Septs: The Clans eventually broke up into a number of distinct septs or groups. These groups were headed by an original member of the clan and dominated a particular part of the countryside. It was not uncommon for septs from the same clan to be found in completely different parts of the country (O'Connor for example) so it is important when researching your roots to try to find out the original part of the country that your ancestors came from as this may be a completely different area from that where the 'major' sept was domicile.

The sept system was an integral part of Gaelic society and survived and was even propagated by the Norman invaders. The system did not survive the English invasion and colonisation of the seventeenth century however, and it became a disadvantage to have a Gaelic sounding name.

Anglicization: The Penal laws that were enforced by the colonists attempted to completely subjugate the Gaelic way of life. It is about this time then, that many Gaelic names changed to their Anglo equivalent or translation. This can cause confusion as many of the names were misinterpreted or misspelled. The name McEaneny for example has a number of variants including McAneny and Bird (the Irish word for bird is éan). Mac an Thomáis was converted to Holmes, Mac Giolla Íosa to MacAleese, etc. The conversion of names beginning with Mac and Mc was even more difficult because the removal of the M sound from the name often completely changed the sound of the name.

The revival of Gaelic consciousness in the later eighteen hundreds saw many Irish families reassume the Mac, Mc, Ó or other Irish form of their names although this was reduced in a number of cases depending on the sound of the name (Kelly is still much more prevalent than O'Kelly, Murphy more prevalent than O'Murphy, etc.)

Surnames today: There are many different origins for Irish names today but the vast majority can be broken down into either of three categories: Gaelic Irish, Cambro-Norman, and finally Anglo-Irish.

The Table below gives a listing of the 100 most commonly names found in Ireland and their meanings. These details were compiled from the 1890 Matheson report.

RankNameGaelic EquivalentMeaningCoat of Arms
1  Murphy ó Murchadhasea-battlerClick Here
 2  Kelly  ó Ceallaighbright-headedClick Here
 3  O'Sullivan  ó Súilleabháin  dark-eyedClick Here
 4  Walsh  Breathnach   WelshmanClick Here
 5  Smith   Mac Gabhann  son of the smith  Click Here 
 6  O'Brien   ó Briain   high, nobleClick Here
 7  Byrne   ó Broin   a ravenClick Here
 8  Ryan   ó Maoilriain   kingClick Here
 9  O'Connor  ó Conchobhair  patron of warriorsClick Here
 10  O'Neill  ó Néill  from Niall of
the Nine Hostages
Click Here
 11  O'Reilly  ó Raghallaigh  Click Here
 12  Doyle   ó Dubhghaill   dark foreignerClick Here
 13  McCarthy  Mac Carthaigh   loving personClick Here
 14  Gallagher  ó Gallchobhair  lover of foreignersClick Here
 15  O'Doherty  ó Dochartaigh   hurtfulClick Here
 16  Kennedy  ó Cinnéide   helmet headedClick Here
 17  Lynch   ó Loinsigh   seafarer, exileClick Here
 18  Murray  ó Muireadhaigh  lord, masterClick Here
 19  Quinn   ó Cuinn   wisdom, chiefClick Here
 20  Moore   ó Mordha   majesticClick Here
 21  McLoughlin  Mac Lochlainn  vikingClick Here
 22  O'Carroll  ó Cearbhaill   valorous in battleClick Here
 23  Connolly  ó Conghaile   fierce as a houndClick Here
 24  Daly   ó Dálaigh assembles frequentlyClick Here
 25  O'Connell  ó Conaill   strong as a wolfClick Here
 26  Wilson  Mac Liam   son of WilliamClick Here 
 27  Dunne   ó Duinn   brownClick Here
 28  Brennan  ó Braonáin   sorrow Click Here
 29  Burke   de Búrca   from Richard de BurghClick Here
 30  Collins  ó Coileáin   young warrior Click Here
 31  Campbell     crooked mouth Click Here
 32  Clarke   óCléirigh   clergyman Click Here
 33  Johnston  Mac Seáin   son of John   Click Here
 34  Hughes  ó hAodha   fire   Click Here
 35  O'Farrell  ó Fearghail   man of valourClick Here
 36  Fitzgerald  Mac Gearailt   spear ruleClick Here
 37  Brown   Mac an Bhreithiún  son of the brehon (judge)   Click Here
 38  Martin  Mac Giolla Mháirtín  devotee of Saint Martin  Click Here
 39  Maguire  Mag Uidhir   dun-coloured  Click Here
 40  Nolan   ó Nualláin   famousClick Here
 41  Flynn   ó Floinn   bright redClick Here
 42  Thompson  Mac Tomáis   son of Thom   Click Here
 43  O'Callaghan  ó Ceallacháin   bright headedClick Here
 44  O'Donnell  ó Domhnaill   world-mighty Click Here
 45  Duffy   ó Dufaigh   dark, black   Click Here
 46  O'Mahony  ó Mathúna   bear-calfClick Here
 47  Boyle   ó Baoill   vain pledge   Click Here
 48  Healy   ó hÉalaighthe   artistic, scientific   Click Here
 49  O'Shea  ó Séaghdha   fine, stately  Click Here
 50  White   Mac Giolla Bháin  of fair complexion   Click Here
 51  Sweeney  Mac Suibhne   pleasant Click Here
 52  Hayes   ó hAodha   fire   Click Here
 53  Kavanagh  Caomhánach   comely, mildClick Here
 54  Power   de Paor   the poor manClick Here
 55  McGrath  Mac Craith   son of graceClick Here
 56  Moran   ó Móráin   greatClick Here
 57  Brady   Mac Brádaigh   spirited   Click Here
 58  Stewart  Stiobhard   one who superintends   Click Here
 59  Casey   ó Cathasaigh   vigilant in war, watchfulClick Here
 60  Foley   ó Foghladh   a plunderer   Click Here
 61  Fitzpatrick  Mac Giolla Phádraig  devotee of Saint Patrick  Click Here
 62  O'Leary  ó Laoghaire   calf-herdClick Here
 63  McDonnell  Mac Domhnaill  world-mightyClick Here
 64  MacMahon  Mac Mathúna   bear-calf   Click Here
 65  Donnelly  ó Donnghaile   brown valour   Click Here
 66  Regan   ó Riagáin   little kingClick Here
 67  Donovan  ó Donnabháin   brown, black   Click Here
 68  Burns     from Scottish Burness   Click Here
 69  Flanagan  ó Flannagáin   red, ruddy  Click Here
 70  Mullan  ó Maoláin   bald   Click Here
 71  Barry   de Barra   Cambro-Norman nameClick Here
 72  Kane   ó Catháin   battlerClick Here
 73  Robinson      son of Robert   Click Here
 74  Cunningham      Scottish nameClick Here
 75  Griffin  ó Gríofa   Welsh: Gruffudd   Click Here
 76  Kenny   ó Cionaoith   fire sprung   Click Here
 77  Sheehan  O'Siodhachain   peacefulClick Here
 78  Ward   Mac an Bhaird  son of the bardClick Here
 79  Whelan  ó Faoláin   wolfClick Here
 80  Lyons   ó Laighin   grey   Click Here
 81  Reid     red haired,
ruddy complexion
  Click Here
 82  Graham      grey home   Click Here
 83  Higgins  ó hUiginn Click Here
 84  Cullen   ó Cuilinn   hollyClick Here
 85  Keane   Mac Catháin    Click Here
 86  King   ó Cionga    Click Here
 87  Maher   Meagher   fine, majestic  Click Here
 88  MacKenna  Mac Cionaoith  fire-sprung   Click Here
 89  Bell   Mac Giolla Mhaoil Click Here
 90  Scott    a Scottish gael   Click Here
 91  Hogan   ó hÓgáin   young   Click Here
 92  O'Keeffe  ó Caoimh   gentleClick Here
 93  Magee   Mag Aoidh   fire  Click Here
 94  MacNamara  Mac Conmara   hound of the sea  Click Here
 95  MacDonald  Mac Dónaill   world-mighty   Click Here
 96  MacDermott  Mac Diarmada  free from jealousy   Click Here
 97  Molony  ó Maolomhnaigh  servant of the Church  Click Here
 98  O'Rourke  ó Ruairc   Click Here
 99  Buckley  ó Buachalla   cow herd   Click Here
 100  O'Dwyer  ó Dubhuir   black  Click Here

Where to Next?

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by Michael Green
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