The following data is from "Irish Families - The Names, Arms and Origins" by Edward MacLysaght. Pub. Irish Academic Press. ISBN 0-7165-2364-7
In America and in England the use of surnames as christian names has become very widespread since the end of the nineteenth century. In Great Britain famous surnames like Cecil, Douglas, Gordon, Leslie and Stanley are now regarded there as recognised christian names and are common as such; while in the United States you are more likely to meet, say, a Calvin D. Smith than a plain Tom Smith. The almost universal initial representing a second forename is, of course, characteristically American. Mr. Harry S. Truman, twice President of the United States (who, by the way, was given a genuine christian name at baptism) is reported to have often said that he did not know what his S. stood for and rather thought it was just an ornamental initial and no more.
In Ireland fancy forenames - we can hardly call Berkeley, Melville, Spencer and the like Christian names - are almost unknown, except in Protestant families of "West British" outlook, with whom in Victorian times the "Castle Catholics" could be coupled. Nor do we find the Old Testament biblical names, once so popular in England, adopted to any appreciable extent in Irish families at any period; and we never had in Ireland anything comparable to the extravagance of the Cromwellian Puritans who condemned their children to bear such extraordinary forenames as "Praise-God", "Christ-died-to-save-us", and the like.
In modern times in Ireland, particularly in Catholic Ireland, christian names are genera1ly chosen from those of saints: but we still have a fair share of old Gaelic personal names in use, such as Brian, Connor, Dermot and Manus, which are not to be found in Irish hagiology. However, most of the old Gaelic names were actually borne by some early Irish saint: the commonest of them today are Aidan, Brendan, Colman, Donough, Fergus, Finbar, Fintan, Kevin, Kieran, Lorcan and Phelim among men, and Brigid, Dympna and Ita among women.
Gaelic names such as those just referred to have become more popular of late years, but the great majority of our people bear christian names which are not of Irish origin; and this has been the case since the destruction of the old Gaelic order. In a number of cases, however, Gaelic names are disguised under the foreign synonyms arbitrarily chosen to represent them. Thus Connor was equated with Cornelius, Cormac and Callagh with Charles, Donough with Denis, Lorcan with Laurence, Se n with John, Liam with William, Éamonn with Edward, Rory with Roger, Teig with Timothy, and, most far-fetched of all, Dermot with Jeremiah. An examination of the Fiants and other late sixteenth century sources shows that Gaelic christian names were still usual up to that time; but from the seventeenth century onwards the conditions now obtaining prevailed, and the only changes to be observed are the waning and waxing of the polarity of certain individual names, while the common use in one part of the country of some which are scarce in another is also an interesting point to which reference will be made further on in this article.
The main conclusion to be drawn is that while John has been, consistently since 1650, the most popular christian name throughout the country, the great popularity of its present day rivals Patrick and Michael is of comparatively recent date. Growing devotion to the Archangel may account for the latter. As regards Patrick it has frequently been stated that it was almost unknown as a christian name before the time of Patrick Sarsfieid and that its widespread adoption can be attributed to the honour in which that celebrated Irish soldier was held. It is, I think, true that the name Patrick was thus first popularised; but it is quite erroneous to say that the name was uncommon before his time. It has been suggested that the mediaeval Gaels had so great a veneration for the patron saint of Ireland that they refrained from giving his name to their sons, just as they did not call their daughters Muire, the Irish name for the Blessed Virgin, Máire being used for Mary, and it is true that the form Giolla Padraig (Gilpatrick) is found in mediaeval records. Nevertheless the Annals, the ecclesiastical registers etc. contain many Patricks from Patrick O'Scannell, Bishop of Raphoe (1261-1265), onwards.
Even within the past half century certain tendencies can be perceived. For County Limerick we have a ready means of comparison without having recourse to the labour of making a count of the voters' lists of fifty years ago: for Father Woulfe published many years before the appearance of his magnum opus an analysis of the names of County Limerick, including the christian names. For the most part their comparative popularity remains much the same, but it is of interest to note that there has been a very marked fall in the number of Jeremiahs, and Bartholomew and Philip share this decline, while a very considerable increase is noticeable in the name Joseph and also, though in a less degree, in Christopher and Martin.
All over the country, and particularly in County Limerick, William is and was a favourite name. The association of William of Orange with a disastrous period of Irish history has surprisingly had no effect on its popularity. On the other hand the odium attaching to Cromwell has made Oliver a hated name in Ireland, but this is offset by the reverence felt for the martyred Oliver Plunkett, especially since his beatification.
As we have seen, the old Irish forenames fell into disuse with the submergence of the Gael. The persecution of the Catholic Church and its adherents, which was an integral part of the policy of conquest, had the effect of making the Irish people more conscious of their religion and stiffened their determination not to relinquish it: it is from this period we may date the practice of calling children by the names of saints.
Every diocese has its patron saint. In some his name is to be found in frequent use as a christian name in that diocese: thus Kierans are quite numerous in the counties embraced by the dioceses of Clonmacnoise and Ossory, but not elsewhere; similarly Brendan is not uncommon in Kerry and Clonfert, Finbar in Cork, Colman in Cloyne, Malachy in Down and Armagh, Eugene in Derry, Kevin and Laurence in Dublin, Phelim in Kilmore and Nicholas in Galway. On the other hand many of them have never been adopted: it is indeed very seldom one hears of a boy called Mel (Ardagh), Jarlath (Tuam), Nathy (Achonry), Munchin (Limerick), Fachanan (Kilfenora and Ross) or Otteran (Waterford). The name of another saint associated with County Waterford, however - St. Declan - is often used in that county, but seldom elsewhere.
Certain christian names are also closely associated with particular surnames. Thus Florence (a curious anglicisation of Finghin or Fineen) suggests MacCarthy and Tiernan O'Rourke. Other familiar combinations are Garrett Fitzgerald, Niall O'Boyle, Myles O'Reilly, Quentin O'Kane, Heber MacMahon, Randal MacDonnell; Aeneas and Manus are association with O'Donnell, and Donough, Kennedy and Lucius with O'Brien, while Boetius was a favourite name with the MacEgans and the MacClancys.
Little has been said about women's christian names. Historically the sources for statistical information are meagre since the records available, dealing as they do with agrarian, ecclesiastical and military affairs, relate almost entirely to men. The modern voters' lists, of course, contain as many women as men, but there are much fewer women's christian names than men's and much less variation geographically. Mary is by far the commonest of these, exceeding even John in numbers. In the seventeenth century it was rare. Brigid, until comparatively recently almost as popular as Mary, has of late years been sadly neglected. Another present-day tendency to be noted is the marked increase in the use of old Gaelic names such as Nuala, Sive, Sheila and Una.
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