Language & meaning
Meaning & Irish forms
Gaelic Gaelic Irish: the royal Mac Diarmada family of Moylurg in Connacht, a branch of the same stock as the O'Connors, with a separate MacDermott family in Inishowen, Co. Donegal.[1][2]
The name is built on the personal name Diarmaid, usually explained as “an ancient Irish personal name; Woulfe glosses it as 'freeman'”. Woulfe calls Diarmaid an ancient and very common name, rendered in English as Dermot, Darby and Jeremiah. He gives the meaning 'freeman' in his entry for Ó Diarmada.[1][7]
Pronunciation
McDermott: mac-DUR-mut
Place
Where the McDermotts lived
How common the name was in each county, as a share of the population, in the three surviving full censuses of Ireland. Use the buttons to compare years.
Share of each county's census population. 1926 covers the 26 counties of the Irish Free State only.
Highest concentration · 1901
Roscommon
151 per 10,000
1,521 McDermotts · 8.83× the national share
Highest share, 1901
Per 10,000 residents. A concentration index above 1 means the name was commoner there than nationally.
Highest concentration · 1911
Roscommon
138 per 10,000
1,294 McDermotts · 8.3× the national share
Highest share, 1911
Per 10,000 residents. A concentration index above 1 means the name was commoner there than nationally.
Highest concentration · 1926
Roscommon
135 per 10,000
1,124 McDermotts · 6.79× the national share
Highest share, 1926
Per 10,000 residents. A concentration index above 1 means the name was commoner there than nationally.
County figures as a table
| County | 1901 | 1911 | 1926 | Per 10k 1901 | Per 10k 1911 | Per 10k 1926 |
|---|---|---|---|---|---|---|
| Antrim | 173 | 188 | — | 4 | 4 | — |
| Armagh | 76 | 67 | — | 6 | 6 | — |
| Carlow | 14 | 14 | 20 | 4 | 4 | 6 |
| Cavan | 276 | 287 | 302 | 28 | 31 | 37 |
| Clare | 110 | 92 | 76 | 10 | 9 | 8 |
| Cork | 34 | 45 | 57 | 1 | 1 | 2 |
| Donegal | 775 | 731 | 733 | 45 | 43 | 48 |
| Down | 86 | 118 | — | 3 | 4 | — |
| Dublin | 723 | 831 | 852 | 17 | 17 | 17 |
| Fermanagh | 175 | 153 | — | 27 | 25 | — |
| Galway | 532 | 505 | 471 | 28 | 28 | 28 |
| Kerry | 13 | 10 | 13 | 1 | 1 | 1 |
| Kildare | 99 | 131 | 103 | 16 | 20 | 18 |
| Kilkenny | 30 | 29 | 19 | 4 | 4 | 3 |
| Laois | 25 | 17 | 23 | 4 | 3 | 5 |
| Leitrim | 450 | 424 | 399 | 65 | 67 | 70 |
| Limerick | 31 | 32 | 43 | 2 | 2 | 3 |
| Londonderry | 381 | 366 | — | 26 | 26 | — |
| Longford | 159 | 159 | 163 | 34 | 36 | 41 |
| Louth | 176 | 116 | 122 | 27 | 18 | 20 |
| Mayo | 402 | 419 | 377 | 20 | 22 | 22 |
| Meath | 169 | 134 | 134 | 24 | 21 | 21 |
| Monaghan | 136 | 160 | 188 | 18 | 22 | 29 |
| Offaly | 63 | 58 | 61 | 11 | 10 | 12 |
| Roscommon | 1,521 | 1,294 | 1,124 | 151 | 138 | 135 |
| Sligo | 391 | 348 | 364 | 49 | 44 | 51 |
| Tipperary | 16 | 26 | 26 | 1 | 2 | 2 |
| Tyrone | 337 | 347 | — | 22 | 24 | — |
| Waterford | 4 | 12 | 7 | 1 | 2 | 1 |
| Westmeath | 161 | 127 | 130 | 26 | 21 | 23 |
| Wexford | 7 | 11 | 12 | 1 | 1 | 1 |
| Wicklow | 42 | 32 | 44 | 7 | 5 | 8 |
Local strongholds in 1911
District Electoral Divisions (300+ residents) where McDermotts made up the largest share of the population. In Munakill, Co. Leitrim, about one resident in 11 was a McDermott.
| DED | County | McDermotts | Share |
|---|---|---|---|
| Munakill | Leitrim | 82 | 9.5% |
| Tulsk | Roscommon | 57 | 7.3% |
| Graffy | Donegal | 72 | 7.1% |
| Island | Galway | 65 | 6.6% |
| Cams | Roscommon | 36 | 6.6% |
| Mountfield | Tyrone | 24 | 6.3% |
| Ballyfermoyle | Roscommon | 33 | 5.9% |
| Kilcolagh | Roscommon | 31 | 5.7% |
Origins
Septs & territories
Many Irish surnames were adopted independently by unrelated families. These are the distinct McDermott lineages described in the sources.
A surname can point you towards a place. On its own, it cannot establish a pedigree.
Mac Diarmada of Moylurg (Clann Mhaoilruanaidh)
Moylurg (Magh Luirg), now roughly the baronies of Boyle and Frenchpark · Roscommon, Sligo
The senior line and overlords of all the MacDermotts, kings of Moylurg with their fortress on the Rock of Lough Key near Boyle. They kept that rank until the end of the 16th century. Afterwards, as successors to the O'Garas, they held lands at Coolavin in Co. Sligo, and their head became known as Prince of Coolavin.[1][8][9][10]
MacDermot Roe (Mac Diarmada Ruadh)
Kilronan parish, with a seat at Alderford near Ballyfarnon · Roscommon
The 'Red MacDermotts'. Woulfe makes their head chief of Tir Thuathail, the parish of Kilronan, living at Alderford. Wikipedia traces the line to Dermot Roe, blinded in 1266, records them as lords of Coilte Conchoghair in the 15th century, and says that by the 16th they held all of Kilronan, including the iron works around Arigna.[1][11][12]
MacDermot Gall (Mac Diarmada Gallda)
Artagh, the parish of Tibohine · Roscommon
The 'English' or anglicised MacDermotts, whose chief held Artagh. Woulfe records them as one of the three branches into which the family divided in the mid-14th century, but gives no further history.[1][13]
Ó Duibhdhíorma of Bredach
Bredach, the eastern half of Inishowen · Donegal
An unrelated Cenél nEógain family, anciently lords of Bredach in Inishowen. Woulfe found them still numerous in Donegal, where the shortened Ó Díorma was commonly anglicised MacDermott.[2]
The name over time
History
Kings of Moylurg
Moylurg, Magh Luirg in Irish, was a sub-kingdom of Connacht in what is now north Roscommon, ruled from about 956 until 1585. Its first king, Maelruanaidh Mór, was a son of Tadg mac Cathail, king of Connacht, and Wikipedia says he gave up his claim to the provincial kingship in return for Moylurg. His descendants, Clann Mhaoilruanaidh, were a branch of the Síl Muiredaig and close kin of the O'Connors; Woulfe ranks them next to the O'Connors as the most powerful family in Connacht. Woulfe places Maolruanaidh in the 11th century, which does not fit Wikipedia's 10th-century dating.[8][1]
From Diarmaid to MacDermott
The surname comes from Diarmaid, a grandson of Maolruanaidh according to Woulfe, who died in 1159; Wikipedia counts him as the seventh king of Moylurg, reigning from 1124. His descendants took the name Mac Diarmada. Its anglicised forms ranged from MacDermott and M'Dermot to Dermody and even Darby, since Diarmaid itself was rendered Dermot, Darby or Jeremiah. Woulfe notes that Connacht speakers usually said Mac Dhiarmada, and Wikipedia lists the Manx Kermode as a descendant of that form.[1][5][4]
The Rock of Lough Key
The MacDermott stronghold stood on Castle Island in Lough Key, the Rock of Loch Cé. The Annals of Loch Cé record that lightning burned the island residence in 1184, killing many, including the wife of the king. In 1235 Richard Mór de Burgh besieged it with a catapult mounted on rafts and then with fire ships, and Cormac MacDermot had to surrender. The family lost the island in 1586. The annals themselves were commissioned by Brian na Carraige MacDermot, who died in 1592, and cover events from 1014 to 1590.[9][14][1]
Three MacDermott septs
Woulfe says that in the mid-14th century the family split into three septs, each with its own chief: MacDermot of Moylurg, overlord of the rest; MacDermot Roe of Kilronan; and MacDermot Gall of Artagh. The baronies of Boyle and Frenchpark, he adds, represent the old MacDermott patrimony. Wikipedia dates the Roe line earlier, to Dermot Roe, blinded in 1266 by the king of Connacht. By the end of the Gaelic period the MacDermots Roe made up about a third of the whole clan.[1][12]
Alderford and O'Carolan
The MacDermots Roe lived at Alderford near Ballyfarnon. They were the chief patrons of the blind harper Turlough O'Carolan, whose family moved to Ballyfarnon at their invitation; Mrs MacDermot Roe had him educated and, after smallpox blinded him, apprenticed him to a harper. Woulfe says O'Carolan died in MacDermottroe's house at Alderford in 1737, while Wikipedia gives 25 March 1738. He lies in the MacDermot Roe crypt at Kilronan. After Charles MacDermot Roe died in 1759, his Protestant brother John evicted his family from Alderford; John's line died out in 1917.[12][11][15]
Princes of Coolavin
Moylurg ceased to exist as a kingdom in the late 16th century, but the senior line survived the confiscations and the Penal Laws. Holding land at Coolavin in south Sligo, a barony the O'Garas had once ruled, its head came to be called Prince of Coolavin by popular usage, first applied to Charles MacDermot (1707–1758). Heads of the family have used it ever since: Rory MacDermot held it from 2003 until his death in 2021, and his son Francis succeeded him.[10][16][4][1]
Places linked to the name
- Lough Key and McDermott's Castle (Loch Cé; Carraig Mhic Dhiarmada), Co. Roscommon — The Rock of Lough Key, on Castle Island, was the MacDermott fortress until 1586.[9][1]
- Boyle (Mainistir na Búille), Co. Roscommon — The barony that, with Frenchpark, Woulfe says represents the MacDermott patrimony.[1]
- Frenchpark (Dún Gar), Co. Roscommon — The second barony of old MacDermott country, containing Artagh, the MacDermot Gall territory.[1]
- Alderford, Ballyfarnon (Béal Átha Fearnáin), Co. Roscommon — Seat of the MacDermots Roe and home of their protégé Turlough O'Carolan.[12][11]
- Coolavin (Cúl ó bhFionn), Co. Sligo — Barony in south Sligo whose name gave the title Prince of Coolavin.[16][10]
- Inishowen, Co. Donegal — Its eastern half, Bredach, was ruled by the Ó Duibhdhíorma family, later called MacDermott.[2]
Everyday lives
The McDermotts in the census
Who the McDermotts were in the 1901 and 1911 censuses (and 1926 where recorded), set against everyone in Ireland in the same census.
McDermotts All of Ireland Ireland's figure marked on the McDermott bar
Religion, 1911
Irish language
44 McDermotts spoke Irish only in 1901.
Reading & writing
Family life, 1911
Commonest occupations
Adults aged 15+, 1901 and 1911 combined.
| Farmer | 1,829 |
| Farmer's son | 790 |
| Farmer's daughter | 385 |
| Agricultural labourer | 222 |
| Labourer | 181 |
| General labourer | 180 |
| Farm servant | 172 |
| Farm labourer | 165 |
| House keeper | 147 |
| Seamstress | 135 |
Born outside Ireland
2.9% of McDermotts in 1911 gave a birthplace outside Ireland.
| England | 154 |
| Scotland | 37 |
| United States | 14 |
| India | 3 |
Median age: 24 in 1901, 27 in 1911.
Given names
First names among the McDermotts
Men and boys
- John1,479
- Patrick1,295
- James900
- Michael870
- Thomas835
- William325
- Edward276
- Peter255
- Joseph244
- Bernard217
Women and girls
- Mary1,573
- Bridget924
- Margaret554
- Catherine422
- Annie400
- Ellen364
- Kate352
- Anne312
- Maggie253
- Elizabeth217
All three censuses combined. Top five in 1926: John, Patrick, Michael, James, Thomas; Mary, Bridget, Margaret, Annie, Kate.
Spellings
Spellings
This page combines the spellings below, which census enumerators and families used for the same name.
| Spelling | 1901 | 1911 | 1926 | Records |
|---|---|---|---|---|
| McDermott | 7,218 | 6,916 | 5,549 | Search |
| MacDermott | 173 | 204 | 192 | Search |
| McDermot | 196 | 163 | 122 | Search |
Related forms
- MacDermott, MacDermot — MacDermot is the spelling used by the Coolavin and Roe lines; Burke has both.[4][17]
- McDermot, M'Dermot — Early and abbreviated spellings recorded by Woulfe.[1]
- MacDermot Roe, MacDermottroe — The Roe ('red') branch of Kilronan and Alderford.[11][12]
- Dermody, Darmody, Darby — Other anglicisations of Mac Diarmada; Dermody and Darby also come from Ó Diarmada.[1][7]
- Kermode — From Mac Dhiarmada; Wikipedia treats it as the Manx form.[5][4]
- MacDiarmid, McDiarmid — Wikipedia lists these Scottish forms as ultimately derived from the Irish name.[4]
Diaspora
The McDermotts abroad
Emigration carried the name worldwide. In the 2010 United States census:
| Spelling | People | US rank |
|---|---|---|
| McDermott | 30,528 | 1151st |
| MacDermott | 399 | 52037th |
| McDermot | 199 | 92358th |
Source: US Census Bureau, 2010 surname file (public domain).
Heraldry
Is there a McDermott coat of arms?
Arms belong to particular families, not to everyone named McDermott. Burke's General Armory records arms for the MacDermots, chiefs of Moylurg: on silver, a red chevron between three blue boars' heads with three gold cross crosslets, a crest of a demi-lion holding a crowned sceptre, and the motto 'Honor probataque virtus'. Burke gives the same arms to the Prince of Coolavin, with the motto 'Honore et virtute', and to MacDermot Roe of Alderford. He also lists different MacDermot arms for other families.[17]
Websites selling a single “McDermott family crest” are selling a design, not an inheritance. Arms in Ireland belonged to individuals and their heirs, and the Chief Herald of Ireland still grants arms that way today.
People
Notable people named McDermott
- Cormac MacDermot (reigned 1218–1244) King of Moylurg who surrendered the Rock of Lough Key to Richard Mór de Burgh in 1235.
- Hugh Hyacinth O'Rorke MacDermot (1834–1904) Lawyer and Prince of Coolavin who served as Attorney-General for Ireland.
- Patrick McDermott (1859–1942) Anti-Parnellite nationalist MP for North Kilkenny from 1891 to 1902.
- Seán Mac Diarmada (1883–1916) Leader of the 1916 Rising and second signatory of the Proclamation, executed after the Rising.
- Frank MacDermot (1886–1975) Barrister, soldier and historian; TD for Roscommon and a founding member of Fine Gael.
- Sir Dermot MacDermot (1906–1989) British ambassador to Indonesia and Thailand, styled Prince of Coolavin.
- Niall MacDermot (1916–1996) British Labour MP who later led the International Commission of Jurists.
- Galt MacDermot (1928–2018) Canadian-American composer of the musicals Hair and Two Gentlemen of Verona.
- Alice McDermott (born 1953) American novelist who won the National Book Award for Charming Billy.
- Dylan McDermott (born 1961) American actor known for The Practice and American Horror Story.
Questions
Questions about the McDermott name
Is McDermott an Irish surname?
Yes. McDermott is the English form of Mac Diarmada, the surname of the kings of Moylurg in north Roscommon, who were a branch of the same royal stock as the O'Connors of Connacht. A separate Donegal family, Ó Duibhdhíorma of Inishowen, also came to be called MacDermott. Wikipedia notes that the name is still most common in the west of Ireland and Roscommon.[1][2][18]
What is McDermott in Irish?
Mac Diarmada, meaning 'son of Diarmaid'. In the spoken Irish of Connacht the usual form was Mac Dhiarmada, according to Woulfe. The older spelling Mac Diarmata is also found. The personal name Diarmaid was rendered in English as Dermot, Darby or Jeremiah.[1][5][4][3]
Are McDermott, MacDermott and MacDermot the same name?
Yes. They are spellings of the same Irish surname, Mac Diarmada, and the choice between Mc, Mac, one 't' or two is a matter of family habit rather than origin. The heads of the family at Coolavin and the MacDermots Roe of Alderford have generally written MacDermot. Dermody and Darby are less obvious anglicisations of the same name.[1][4][10]
Who is the Prince of Coolavin?
The title is a style that arose by popular usage rather than an official grant, used by the head of the MacDermots, descendants of the kings of Moylurg. It was first applied to Charles MacDermot (1707–1758) and has passed down the senior line. Rory MacDermot held it from 2003 until his death in 2021, when his son Francis succeeded him.[10][4]
Is there a McDermott family crest or motto?
Not one for everyone named McDermott. Burke's General Armory records arms for the MacDermot chiefs of Moylurg, a red chevron between three boars' heads on silver, with the motto 'Honor probataque virtus' ('honour and tested virtue'). For the Prince of Coolavin he gives the same arms with 'Honore et virtute'. Other MacDermot families had different arms.[17]
Where does the McDermott name come from?
From Moylurg in north Co. Roscommon, around Lough Key and the town of Boyle, roughly the modern baronies of Boyle and Frenchpark. The MacDermots Roe were based at Kilronan and Alderford, and the senior line later at Coolavin in south Sligo. Some Donegal MacDermotts descend instead from the Ó Duibhdhíorma family of Inishowen.[1][12][10][2]
Where in Ireland is the McDermott surname most common?
In the 1911 census the largest numbers of McDermotts lived in Roscommon (1,294), Dublin (831), Donegal (731). Relative to population, the name was most concentrated in Roscommon (138 per 10,000), Leitrim (67 per 10,000), Sligo (44 per 10,000).
How common was the McDermott surname in Ireland?
7,283 people were recorded as McDermott or MacDermott or McDermot in the 1911 census of Ireland, making it the 95th most common surname. That is roughly 0.2% of the population, or 1 person in 602.
Looking for a McDermott ancestor?
Search every McDermott household in the 1901, 1911 and 1926 censuses, with free images of the original forms.
Evidence
Sources
- Patrick Woulfe, Mac Diarmada, in Irish Names and Surnames (1923)
- Patrick Woulfe, Ó Duibhdhíorma, in Irish Names and Surnames (1923)
- Gaois research group, Dublin City University, Sloinnte (surname database), version 2 (2022). Cluster 'Diarmaid': Mac Diarmada = McDermott.
- Wikipedia, Mac Diarmada (2026)
- Patrick Woulfe, Mac Dhiarmada, in Irish Names and Surnames (1923)
- Patrick Woulfe, Anglicisation of Irish Surnames, in Irish Names and Surnames (1923)
- Patrick Woulfe, Ó Diarmada, in Irish Names and Surnames (1923)
- Wikipedia, Magh Luirg (2026)
- Wikipedia, McDermott's Castle (2026)
- Wikipedia, Prince of Coolavin (2026)
- Patrick Woulfe, Mac Diarmada Ruadh, in Irish Names and Surnames (1923)
- Wikipedia, MacDermot Roe (2026)
- Patrick Woulfe, Mac Diarmada Gall, in Irish Names and Surnames (1923)
- Wikipedia, Annals of Loch Cé (2026)
- Wikipedia, Turlough O'Carolan (2026)
- Wikipedia, Coolavin (2026)
- Sir Bernard Burke, The General Armory of England, Scotland, Ireland, and Wales (1884). Entries 'Mac Dermot (Chiefs of Moylurg)', 'McDermot (Coolavin)', 'McDermot (Mac Dermott Roe; Alderford)' and other MacDermot and McDermott entries.
- Wikipedia, McDermott (2026)
- Census of Ireland 1901 and 1911, and Census of Population 1926, National Archives of Ireland. Counts compiled by surnames.ie from the irishcensus.com transcription (dataset 20260831130351). 1926 data © National Archives of Ireland, CC BY 4.0.
How we compile these figures: methodology.