# Where did the "O" come from in Irish names? **URL:** \ **Category:** Factual Questions\ **Created:** [March 19, 2003, 2:18pm UTC](https://boards.straightdope.com/t/where-did-the-o-come-from-in-irish-names/162542 "2003-03-19T14:18:37Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![Phlosphr](https://avatars.discourse-cdn.com/v4/letter/p/c68b51/32.png) [@Phlosphr](https://boards.straightdope.com/u/Phlosphr)\ **Post date:** [March 19, 2003, 2:18pm UTC](https://boards.straightdope.com/t/where-did-the-o-come-from-in-irish-names/162542/1 "2003-03-19T14:18:37Z")
O’Connor, O’Reilly, O’Shannon, O’ My God? I have always wondered this secretly and have never asked my Irish American neighbors why the O. Ah to be sure! there must be a good reason… So Irish friends… Why O’Why is their an O before some names? ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [March 19, 2003, 2:20pm UTC](https://boards.straightdope.com/t/where-did-the-o-come-from-in-irish-names/162542/2 "2003-03-19T14:20:51Z")
It’s a contraction of “Of”, so I’ve been told, which is why the apostrophe. ---
**Author:** ![pierre72](https://avatars.discourse-cdn.com/v4/letter/p/b2d939/32.png) [@pierre72](https://boards.straightdope.com/u/pierre72)\ **Post date:** [March 19, 2003, 2:22pm UTC](https://boards.straightdope.com/t/where-did-the-o-come-from-in-irish-names/162542/3 "2003-03-19T14:22:04Z")
IANAI (I am not an Irishman), but I believe it’s a shortening of “of” - as in “son of”, just as Mc / Mac in Scotland. On occasion it could be “of” as in “who comes from”… ---
**Author:** ![pravnik](https://avatars.discourse-cdn.com/v4/letter/p/8edcca/32.png) [@pravnik](https://boards.straightdope.com/u/pravnik)\ **Post date:** [March 19, 2003, 2:26pm UTC](https://boards.straightdope.com/t/where-did-the-o-come-from-in-irish-names/162542/4 "2003-03-19T14:26:28Z")
It’s a patronymic affix from “ua”, which means “descendant of.” Sort of like the -son in “Davidson.” ---
**Author:** ![MC\_Master\_of\_Ceremonies](https://avatars.discourse-cdn.com/v4/letter/m/bb73d2/32.png) [@MC\_Master\_of\_Ceremonies](https://boards.straightdope.com/u/MC_Master_of_Ceremonies)\ **Post date:** [March 19, 2003, 2:30pm UTC](https://boards.straightdope.com/t/where-did-the-o-come-from-in-irish-names/162542/5 "2003-03-19T14:30:05Z")
Pravnik’s correct, but Pierre72, Mac is actually an Irish prefix meaning ‘son of’ that migrated to Scotland with the Dalriadan Scots, but manyu Irish names still have it as a prefix. ---
**Author:** ![Phlosphr](https://avatars.discourse-cdn.com/v4/letter/p/c68b51/32.png) [@Phlosphr](https://boards.straightdope.com/u/Phlosphr)\ **Post date:** [March 19, 2003, 2:30pm UTC](https://boards.straightdope.com/t/where-did-the-o-come-from-in-irish-names/162542/6 "2003-03-19T14:30:23Z")
So it means from…? and Mc and Mac mean from as well but in Scottish? ---
**Author:** ![BMalion](https://avatars.discourse-cdn.com/v4/letter/b/e274bd/32.png) [@BMalion](https://boards.straightdope.com/u/BMalion)\ **Post date:** [March 19, 2003, 2:37pm UTC](https://boards.straightdope.com/t/where-did-the-o-come-from-in-irish-names/162542/7 "2003-03-19T14:37:52Z")
Also, (going from memory from history of Scot/Irish naming conventions I studied long ago)… “Mic” _son of_ “Mac” _son of_ “Nic” _daughter of. as in Padrigin NicTorkelson, Padrigin, daughter of Torkelson_ “O” _son of_ “U” _son of. as in U’Seanin…son of Sean_ “Mc” _son of_ Most of these are derivations of the Gaelic words, though I think that “Nic” and “U” are of Norse origins. ---
**Author:** ![pierre72](https://avatars.discourse-cdn.com/v4/letter/p/b2d939/32.png) [@pierre72](https://boards.straightdope.com/u/pierre72)\ **Post date:** [March 19, 2003, 2:41pm UTC](https://boards.straightdope.com/t/where-did-the-o-come-from-in-irish-names/162542/8 "2003-03-19T14:41:02Z")
> [@](#): > > \*Originally posted by MC Master of Cermonies \* > \*\*Pravnik’s correct, but Pierre72, Mac is actually an Irish prefix meaning ‘son of’ that migrated to Scotland with the Dalriadan Scots, but manyu Irish names still have it as a prefix. \*\* Ah - thanks. That’ll teach me for generalising, eh? 🙂 ---
**Author:** ![jjimm](https://avatars.discourse-cdn.com/v4/letter/j/ba8739/32.png) [@jjimm](https://boards.straightdope.com/u/jjimm)\ **Post date:** [March 19, 2003, 2:42pm UTC](https://boards.straightdope.com/t/where-did-the-o-come-from-in-irish-names/162542/9 "2003-03-19T14:42:45Z")
I’m not entirely sure of the actual word from which it comes, but it’s derived from the Irish language, and is _definitely not_ a contraction of the English word “of”. ---
**Author:** ![manwithaplan](https://avatars.discourse-cdn.com/v4/letter/m/f1d935/32.png) [@manwithaplan](https://boards.straightdope.com/u/manwithaplan)\ **Post date:** [March 19, 2003, 3:42pm UTC](https://boards.straightdope.com/t/where-did-the-o-come-from-in-irish-names/162542/10 "2003-03-19T15:42:59Z")
**BMalion** , in Ireland ‘Ní’ (pronounced knee) is often used instead of ‘Nic’. I’m no Irish scholar but I always thought it had the same root as ‘iníon’ (in Ian) which is Irish for daughter. You also have ‘Uí’ (ee) or ‘Bean Uí’ which is used to denote ‘wife of’. ‘Ó’ is the Irish for ‘from’ which probably has a similar derivation to that described by **pravnik**. In many ‘proper’ Irish surnames Ó is used but it is represented as O’ (with an apostrophe) in anglicised versions e.g. Ó Raghaillaigh becomes O’Reilly. **Phlosphr** In Irish, Mac means ‘son’ rather than from (Mc is an anglicised contraction). I presume Scots Gaelic is similar. MWAP (who’s an O’ in real life and nearly failed Irish at school) ---
**Author:** ![elfje](https://avatars.discourse-cdn.com/v4/letter/e/e19b73/32.png) [@elfje](https://boards.straightdope.com/u/elfje)\ **Post date:** [March 19, 2003, 5:03pm UTC](https://boards.straightdope.com/t/where-did-the-o-come-from-in-irish-names/162542/11 "2003-03-19T17:03:38Z")
manwithaplan is correct, Ni is only used by girls and as a prefix it means daughter of. Mac or MC means son of, but i have always been told that O’ means “grandson of…” (by an Irish person, I figured before it was just bastardised “of”, meaning “from”, as manwithaplan states… ---
**Author:** ![Dogface](https://avatars.discourse-cdn.com/v4/letter/d/9d8465/32.png) [@Dogface](https://boards.straightdope.com/u/Dogface)\ **Post date:** [March 19, 2003, 5:27pm UTC](https://boards.straightdope.com/t/where-did-the-o-come-from-in-irish-names/162542/12 "2003-03-19T17:27:53Z")
> [@](#): > > \*Originally posted by Q.E.D. \* > \*\*It’s a contraction of “Of”, so I’ve been told, which is why the apostrophe. \*\* Nope. Indeed, the apostrophe is wrong–something added by the English, who mistook a fada for an apostrophe. For example, “O’Brien” should be “Ó Brien”, likewise for “Ó Conor”, etc. But note that it’s “Mac Gobhain”, not “Ó Gobhain” for a very old and well-established Irish name. (Yes, that whole "mac is Scottish and o is irish thing is also false.) The “Ó” was originally spelled “Ua”, which means “descendent in the line”. Thus, Eoin Ó Mahoney would be a man who was a descendent of the original Irish hero Mathuin. [http://scripts.ireland.com/ancestor/magazine/surname/](http://scripts.ireland.com/ancestor/magazine/surname/) Oh, and the “Dalriadian Scots” didn’t immigrate from Scotland. The Dal Riada was founded by (mostly) Ulster Irish who invaded Scotland from the west. ---
**Author:** ![pravnik](https://avatars.discourse-cdn.com/v4/letter/p/8edcca/32.png) [@pravnik](https://boards.straightdope.com/u/pravnik)\ **Post date:** [March 19, 2003, 6:07pm UTC](https://boards.straightdope.com/t/where-did-the-o-come-from-in-irish-names/162542/13 "2003-03-19T18:07:16Z")
> [@](#): > > \*Originally posted by elfje \* > **manwithaplan is correct, Ni is only used by girls and as a prefix it means daughter of. > Mac or MC means son of, but i have always been told that O’ means “grandson of…” (by an Irish person)** Yes, that’s my understanding as well. “Ua” means “descendant”, or more technically, “grandson.” Brian Boru had no surname, but his grandson bore the surname “Ua Brian,” or “grandson of Brian.” Today this is “O’ Brian.” ---
**Author:** ![ruadh](https://avatars.discourse-cdn.com/v4/letter/r/d2c977/32.png) [@ruadh](https://boards.straightdope.com/u/ruadh)\ **Post date:** [March 19, 2003, 11:12pm UTC](https://boards.straightdope.com/t/where-did-the-o-come-from-in-irish-names/162542/14 "2003-03-19T23:12:46Z")
> [@](#): > > \*Originally posted by manwithaplan \* > **BMalion, in Ireland ‘Ní’ (pronounced knee) is often used instead of ‘Nic’… You also have ‘Uí’ (ee) or ‘Bean Uí’ which is used to denote ‘wife of’.** Unmarried women: _Ní_ is to _Ó_ as _Nic_ is to _Mac_. Married women: _Uí_ is to _Ó_ as _Mhic_ is to _Mac_. Don’t worry, I can never keep it straight either 😃