O'Dermonde History, Family Crest & Coats of Arms

Today's Irish surnames are underpinned by a multitude of rich histories. The name O'Dermonde comes from the Irish Gaelic Mac Diarmada, which means "son of Diarmuid," or, son of Dermot and belongs to the venerable Irish tradition of patronymic naming. However another source claims the name came from the Irish diarmaid, which meant "the god of arms." [1]

Early Origins of the O'Dermonde family

The surname O'Dermonde was first found in County Roscommon (Irish: Ros Comáin) located in central Ireland in the province of Connacht, where the family is believed to have been descended from the Heremon dynasty of Irish Kings and were known as the Princes of Moylurg, or the Kings of Connacht, known as the Clann Mulroona. Specifically they were descended from Teige, a King of Connacht and his son, Murtogh, Prince of Moylurg. Their ancient territories were in the counties of Roscommon and Galway. They were divided into three septs. One of the septs embraced English rule early and relatively painlessly, the other two suffered at the hands of Strongbow's invasion in the 12th century. Of the other two septs, the more prominent is based in Coolavin, in Sligo. This sept was originally found at Moylurg and controlled a large part of Roscommon.

"The MacDermotts were ancient Princes of Moylurg, having their territories in the Barony of Boyle, County Koscommon, and parts of the Parishes of Islandeady, Turlough and Breaffy, in Counties Sligo and Mayo. Their chief fortress "was on an island in Lough Key, near Boyle," and they were hereditary Marshals of Connaught. At the present time Connaught is the province in which the MacDermotts are principally found, and half of the persons of the name in that province belong to County Roscommon. " [2]

The head of this branch was one of the few leaders who is still credited as an authentic chieftain by the Genealogical Office of Ireland, conferring the rightful title The MacDermot. Moreover, the chief is also unofficially styled Prince of Coolavin. The third sept held a family seat at Kilronan in the north of Roscommon, and was referred to as MacDermot Roe, from the word ruadh, which means "red."

Early History of the O'Dermonde family

This web page shows only a small excerpt of our O'Dermonde research. Another 119 words (8 lines of text) covering the years 1172, 1251, 1320, 1641, 1592, 1717, 1707 and 1717 are included under the topic Early O'Dermonde History in all our PDF Extended History products and printed products wherever possible.

O'Dermonde Spelling Variations

A name was often recorded during the Middle Ages under several different spelling variations during the life of its bearer because literacy was rare there was no real push to clearly define any of the languages found in the British Isles at that time. Variations found of the name O'Dermonde include Dermott, Dermot, Dermitt, Dermit, McDermott, Dermutt, Dermut, MacDermott, McDermot, MacDermot, MacDermitt, McDermitt, MacDermit and many more.

Early Notables of the O'Dermonde family (pre 1700)

Another 36 words (3 lines of text) are included under the topic Early O'Dermonde Notables in all our PDF Extended History products and printed products wherever possible.

Migration of the O'Dermonde family

Ireland became inhospitable for many native Irish families in the 19th centuries. Poverty, lack of opportunities, high rents, and discrimination forced thousands to leave the island for North America. The largest exodus of Irish settlers occurred with the Great Potato Famine of the late 1840s. For these immigrants the journey to British North America and the United States was long and dangerous and many did not live to see the shores of those new lands. Those who did make it were essential to the development of what would become two of the wealthiest and most powerful nations of the world. These Irish immigrants were not only important for peopling the new settlements and cities, they also provided the manpower needed for the many industrial and agricultural projects so essential to these growing nations. Immigration and passenger lists have documented the arrival of various people bearing the name O'Dermonde to North America: Jo Dermott who settled in Virginia in the year 1635 at the age of 21; John, Thomas, James, and William Dermot settled in Philadelphia, Pennsylvania between 1774 and 1804.



The O'Dermonde Motto +

The motto was originally a war cry or slogan. Mottoes first began to be shown with arms in the 14th and 15th centuries, but were not in general use until the 17th century. Thus the oldest coats of arms generally do not include a motto. Mottoes seldom form part of the grant of arms: Under most heraldic authorities, a motto is an optional component of the coat of arms, and can be added to or changed at will; many families have chosen not to display a motto.

Motto: Honor probataque virtus
Motto Translation: Honour and approved valour.


  1. ^ O'Hart, John, Irish Pedigrees 5th Edition in 2 Volumes. Baltimore: Genealogical Publishing Company, 1976. Print. (ISBN 0-8063-0737-4)
  2. ^ Matheson, Robert E., Special Report on Surnames in Ireland with Notes as to Numeric Strength, Derivation, Ethnology, and Distribution. Dublin: Alexander Thom & Co., 1894. Print


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