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O'Dea, O'Day, Dee, Dea, Day, Daw, O'Die, O'Dawe, Godwin and Goodwin


Ua Déaghaidh, O'Déaghaidh, Ni Dhéaghaidh, and Diaghaidh

The Irish name O'Dea is derived from the Gaelic O'Déaghaidh Sept that was located in County Clare in the West of the country.  The name O'Dea is a name associated alike in the past and present almost exclusively with the County Clare and areas such as Limerick City and North Tipperary which immediately adjoin it.  There are a number of variants of this name including Day, O'Dee, Daw and even Godwin in County Mayo.


 During the early centuries of the first millennium A.D., lands were allotted to the various Celtic clans of noble pedigree.  The O'Deas became lords of the part of North West Clare between the river Fergus to the East, the Burren to the North, and the Atlantic Ocean to the West.

It is in the Western Counties that the majority of the descendants can still be found.  This is indicated by the place names Tully O'Dea and Dysert O'Dea, the site of the famous battle in 1318.

O'Dea History and The Battle of Dysert O'Dea, 1318

For More Information on the O'Dea Clan and History, Follow the Following Links:


                                 Clan O'Dea Web Site 

                             Dysert O'Dea Castle Web                          

                            Message Board Dysert O'Dea                             

                        O'Dea Family Genealogy Forum


  The head of the sept was chief of a considerable territory comprising much of the barony of Inchiquin.  In Gaelic the name is O'Déaghaidh.  This is pronounced O D(y)aw, hence the variant Daw in English.  The pronunciation of the name in English is O'Day and in some places it is anglicized as Day, but Days are not numerous in Ireland and some may be English extraction since Day is a common name in England.  A variant in Gaelic, found in Counties Tipperary and Waterford is O'Diaghaidh anglicized as Dee or O'Dee.  Some O'Deas call themselves O'Dee, this pronunciation arose during the period when things Irish were unfashionable.  The prefix O is now almost always used, but a century ago Dea was quite usual and the English Day was regarded as synonymous.

Surnames originally had specific meanings.  For example, the very earliest use of surnames identified a person's clan such as Dal gCais, otherwise called the Dalcassians after the great leader Cormac Cas Degade, with individuals using one name within the clan.  The early Irish names were usually descriptive, such as Dea-God or Godliness.  Basically surnames evolved from four sources, such as location, occupation, distinguishing characteristics and patronymic.

 The Original Spelling of the   Surnames:                                                    

Ua Déaghaidh (O'Day) =    Grandson of Déaghadh                                        

Later in the 18th Century it Changed Slightly to:                                        

O'Déaghaidh (O'Day) =    Descended from Déaghadh

The Female Equivalent Was Always:

Ni Dhéaghaidh (Nee Yea) =    Daughter of Déaghaidh

The O'Deas were one of the first families in Europe to adopt a surname, during the reign of King Brian Boru who made it compulsory for all noble families, in order to avoid later genealogical confusion.  

The chief who gave his own personal name to Clan O'Dea was Déaghaidh (pronounced Day) who is referred to in Keating's History of Ireland under the year 934 A.D where he describes the rescue of Ceallachán (King of Munster) from his capture on a Viking ship at Dundalk. "Cinneide (Brian Boru's father) also brought five hundred men from   Dal gCais (Co. Clare( under Déaghaidh son of Domhnall (ancestor of the O'Deas) together with those who came from the other free clans of Munster". 

 At the bottom of the page, you will find the link to additional O'Dea information.                     















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