Gaelic Surnames

Rev Patrick Woulfe

Gaelic surnames comprise surnames of Irish, Scottish-Gaelic, and Manx origin.

Irish surnames came into use gradually from about the middle of the tenth to the end of the thirteenth century, and were formed from the genitive case of the names of ancestors who flourished within that period, by prefixing Ó (also written Ua) or Mac (sometimes written Mag*), as:

Ó Briain, Mac Aodhagáin,
Ó hAodha, Mac Cárthaigh,
Ó Néill, Mag Uidhir.

Ó literally signifies a grandson, and Mac a son: but in the wider sense which they have acquired in surnames both now mean any male descendant. The only difference between a surname commencing with Mac and one commencing with Ó is that the former was taken from the name of the father and the latter from that of the grandfather of the first person who bore the surname. Mac-surnames are, generally speaking, of later formation than Ó-surnames.

Surnames were frequently formed, not from the real name of the ancestor, but from some other designation, as rank, trade, occupation, etc., as:

Ó Gobhann (descendant of the smith),
Ó hÍceadha (descendant of the healer),
Mac an Bháird (son of the bard),
Mac an tSaoir (son of the craftsman).

The Gaels of Scotland belonged by race and language to the Irish nation, bore the same or similar personal names, and formed their surnames in the same manner as the Irish from the names or designations of their ancestors. Scottish-Gaelic surnames are, however, of much later date than Irish surnames. The instances of the use of Ó are very rare.†

The Manx language is closely allied to the Irish and Scottish-Gaelic. Manx surnames were formed in the same manner as Irish surnames, by prefixing Mac. Ó, however, was not used. The modern spelling is very corrupt, Mac being generally represented by an initial C or K.

The Danes and Norsemen who settled in Ireland in the ninth and tenth centuries took surnames after the Irish fashion, by prefixing Ó or Mac to the genitive case of the names of their ancestors; but the surnames so formed are in nowise distinguishable from the surnames adopted about the same time by Irish families. What are called Danish surnames are merely surnames formed from a Danish eponym, which, however, owing to the interchange of names, was, at the period when surnames were formed, no longer a sure indication of nationality. The following are examples of this class of surname:

Ó hArailt, Mac Amhlaoibh,
Ó Bruadair, Mac Íomhair,
Ó Dubhghaill, Mac Oitir.

Many Scottish and Manx surnames are of this hybrid class.

* Mag is used before vowels, the consonants c, g, l, n, and r, and the aspirated consonants ḃ, ḋ, ḟ, ṁ, ṡ, ṫ, but not always even before these.

N.B. The above aspirated (dotted or lenited) consonants have been changed to bh, dh, fh, mh, sh, and th, in this online version

† Down to the eighteenth century, the Irish and the Scottish Gaels had a common literary language, though the spoken tongues had diverged considerably. In that century Scottish Gaelic broke completely with the Irish and began a literary career of its own. The spelling of surnames in modern Scottish Gaelic is consequently somewhat difierent from what it would be in Irish. The Scottish surnames included in this book are given in the Irish spelling.