History and Language Irish Surname Guide


A guide to Irish surnames begins with a lesson in history, then one in language.   The two, history and language, are codependent.  Irish surnames are confusing enough, with all the Mc’s, Mac’s and O’s.  However, to truly understand why Irish surnames are so complicated, you have to take a healthy dose of history.  From there, you should feel confident about tracing your Irish Roots and learning about your

Irish genealogy

… ok, you won’t feel confident, but the concept of Irish surnames should be clear as mud for you.  We can promise that much.


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are complete without a clear impression that the Irish were Gaelic.  In Gaelic times, which would be the same as Ancient Times, if you want to get technical, people were called by one name and one name only.  Niall, Eoinn or Art all sufficed.   Keep in mind that with little medical technology, people died very young in ancient times.  Irish surnames weren’t needed since the population was so small.   As times changed, the need to addend how children were named became evident.

The easiest solution to Irish surnames was to add a prefix.  Hence, Mac and O were developed as the first Irish surnames.  Mac, often abbreviated to Mc, means son.  Ó means grandson of.   So, Ó Niall would be grandson of Niall.  Mac Niall would be son of Neil.  That’s simple enough, right?

During Elizabethan times (we’ll avoid an over indulgence in history here: it was the seventeenth century), the English speaking clerks who recorded the names mistook the Gaelic word Ó for the English word ‘of,’  changing many names to O’Niall, which is fairly similar to how we use the Irish surname today.  You should note the change was the use of an apostrophe, whereas Gaelic language used a dash above the Ó.  This, obviously, had a huge historical significance as we continue to use an apostrophe in Irish surnames today.

Anglicization also had a more important, powerful, change.  As Irish surnames go, you would assume the Irish would have kept their Gaelic roots.   However, during the colonization, again of the seventeenth century, it was a huge disadvantage to have an Irish surname.   Clans began changing their Irish surnames to be more English.   Ó Niall became O’Neil.  If you had a name in Gaelic like ó Duinn, meaning brown, it became Brown.  A Gaelic last name meaning bird became Bird.  You might presume names with a longer meaning, like ‘strong as a wolf’ (O’Connell) might have simply become ‘Wolf’ or been changed from the Gaelic Ó Conaill to O’Connell.  Therefore, one clan or family, could have split into two, or three, different Irish surnames.

If you’re researching the history of your Irish surname, or even

tracing your roots and Irish genealogy

as you take an

Ireland vacation

, you will need to consider a few more points.   For example, O’Connor wasn’t just from the North of Ireland.  There could also be an O’Connor in the South of Ireland.  However, during Anglicization the O’Connors in the South could have changed their names to Bird or Brown to keep from being murdered by tyrannous invaders, while the North went a completely different route to simply changing the spelling.

NOTE: Be sure you trace your Irish surname to the area your clan came from if at all possible.

Other traditions besides Irish surnames did remain intact.   You’ll find that clans maintained a crest, or coat of arms chock full of

Irish symbols

.  On a trip to Ireland,  you may also realize that kilt tartans (plaid patterns) and Aran sweater stitching had familial meaning.  If tracking your

Irish genealogy

based on your Irish surname and family location isn’t proving to be effective, try researching a kilt tartan or coat of arms.  We’ll do our best to explain those aspect of Irish heritage too.  We promise that when you’re done reading they, too, will be clear as mud.



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