Top 100 Irish last names explained

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

(O) Kelly - Ó Ceallaigh (The derivation of Kelly is uncertain: the most probable suggestion is that is from ceallach, strife) The most important and numerous sept of this name is that of the Uí Maine. Kelly is the second most numerous name in Ireland. In 1890 less than one percent of them had the prefix O but this has been to some extent resumed.

Mac Kenna - Kennagh  Mac Cionaoith. A branch of the southern Uí Neill, mainly located in Co. Monaghan where they were lords of Truagh; the name is now fairly numerous also in Leinster and Munster. Locally in Clare and Kelly the last syllable is stressed, giving the variants Kennaw, Ginna, Gna, etc.

Kennedy- Ó Cinnéide (ceann, head-éidigh, ugly). An important Dalcassian sept of east Clare which settled in north Tipperary and spread thence far as Wexford whence came the family of President J.F. Kennedy. The Scottish Kennedys are by remote origin Irish Gaels.

Lawless - Laighléis (from the Old-English laghles, outlaw). The name, introduced into Ireland after the Anglo-Norman invasion, is now numerous in Co.s Dublin and Galway. It was one of the ‘Tribes of Kilkenny’ but has now no close association with the city.

(O) Leahy - Ó Laochdha (laochda, heroic). This name is very numerous in Munster but not elsewhere It is basically distinct from Lahy though they have been used synonymously.

(O) Leary - Ó Laoghaire. (Laoghaire was one of the best-known personal names of Ancient Ireland). A sept of the Corca Laoidhe established in Muskerry, of importance in all fields of national activity, especially in literature, and in the military sphere both at home and as the Wild Geese.

(O) Lemon - Lenna  Ó Leannáin (possibly from leann, a cloak or mantle; leanán, paramour, has also been suggested). This is the name of several distinct septs located respectively in Co.s Cork, Fermanagh, and Galway. The last named is of the Sodhan pre-Gaelic stock. The Fermanagh family were erenaghs of Lisgoole. Ó Leannáin is also used as a synonym of Lineen (Ó Luinín), another Fermanagh erenagh family. Further confusion arises from the fact that these have been widely changed to the English name Leonard.

Mac Loughlin - Mac Lochlainn (from a Norse personal name). Of Inishowen. A senior branch of the Northern Uí Néill. They lost their early importance as a leading sept of Tirconnell in the thirteenth century, but are still very numerous in their original homeland-Co.s Donegal and Derry-where their name is usually spelt MacLaughlin; MacLoughlin, also numerous, is more widespread. Minor septs in Connacht were akin to the MacDermota and the O’Connors.

Mac Mahon - Mac Mathghamhna mod. Mac Mathúna (mathghamhan, bear) Thename of two septs, both of importance. That of Thomond descends from Mahon O’Brien, grandson of Brian Ború. MacMahon is now the most numerous name in Co. Clare. In later times the majority of the many of the name were from the Co. Monaghan, where McMahons are numerous today, though less so in Thomond.

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