_O’Beirne._ _O_, for _ua_, a grandson, a descendant; _beirne_, genitive
of _beirn_, a child. Grandson of a child.
_O’Brien._ _O_, descendant; _Brien_, corruption of _Britain_. Grandson of
a Briton. O’Bryan, of similar signification.
_O’Connell._ _Ua Connaill_, from _ua_, grandson; _Connaill_ from _conn_,
of heroes, and _aille_, of a cliff. Descendant of Connell; grandson of
heroes of the cliff.
_O’Connor._ _O_, descendant; _Connor_, from _conn_, of heroes, _cub́ar_,
fond of. Grandson of Connor; descendant of those fond of heroes.
O’Conner, slightly modified form.
_O’Daley._ _O_, grandson; _dalaiǵ_, genitive of _dalać_, a blind fellow.
Descendant of a blind man.
_O’Dare._ _O_, descendant; _dara_, genitive of _dair_, the oak. Grandson
of Dare.
_O’Dea._ _O_, descendant; _Dea_, of God. Descendant of God. O’Day, an
obscure form of the name.
_O’Donovan._ _O’Don-a-b́ean_, from _o_, grandson; _dona_, unfortunate;
_a_, of; _b́ean_, woman. Descendant of an unfortunate woman. O’Donovan,
of like significance.
_O’Donnell._ _Ua Doḿnaill_, from _ua_, descendant; _Doḿnaill_, of
Donnell. Grandson of Donnell; a descendant of Christ. O’Donal, an
abbreviated form of the name. See McDonnell.
_O’Farra._ _O_, descendant; _fara_, genitive of _fear_, a man. Grandson
of man.
_O’Farrell._ _O_, grandson; _fara_, of man; _aille_, of cliff. A
descendant of the man of the cliff.
_O’Gara._ _O_, descendant; _gara_, genitive of _gearr_, a noun derived
from an adjective of the same name, meaning shortness. Grandson of a
short person.
_O’Gorman._ _O_, grandson; _Gorman_, a blue-eyed person. Descendant of a
blue-eyed person.
_O’Grady._ _O_, descendant; _graid́e_, genitive of _grad́_, affection;
_y_ for _eać_, an individual. Grandson of Grady; descendant of an
affectionate person.
_O’Hara._ _O_, grandson; _hara_, Irish genitive of the Anglo-Saxon noun
_hara_, a hare. Descendant of a hare.
_O’Kee._ _O_, descendant; _Kee_, corruption of _Mac Aoid́_, pronounced
_Mac Eey_, son of Hugh. Grandson of the son of Hugh.
_O’Keef._ _O_, offspring; _caoiḿ_, gentle. Descendant of the gentle.
O’Keef, O’Keeffe, analogous words.
_O’Kelley._ _O_, descendant; _Kelley_, from _caillaiǵ_, genitive of
_cailleać_, an old woman, a hag. Grandson of an old woman.
_O’Leary._ _O_, grandson; Anglo-Saxon _lǽr_, learning; Irish _y_ for
_eać_, an individual. Descendant of an educated person.
_O’Lone._ _O_, descendant; _luain_, genitive of _luan_, a warrior.
Grandson of a warrior.
_O’Lochlin._ _O_, grandson; _loiće_, genitive of _loć_, pronounced
_loch_, a lake; _linn_, a swamp. Descendant of Lochlin. O’Loughlin,
O’Laughlin, cognate terms.
_O’Malachlyn._ _O’McLochlin_, from _o_, descendant; _McLochlin_, son of
Lochlin. Descendant of McLochlin.
_O’Mara._ _O_, descendant; _mara_, genitive of _muir_, the sea. Offspring
of the sea. O’Meara, most generally in use.
_O’Millin._ _O_, offspring; _muillin_, of the mill. Descendant of the
mill. O’Mullen, O’Mullane, derivable from the same roots.
_O’Neill._ _Ua Neill_, from _ua_, grandson; _Neill_, genitive of _Niall_,
Neill. Descendant of Neill. O’Neil, O’Neal, quite commonly occur, and are
similarly derived.
_Oram._ _Or_, gold; _am_, time. Time is gold; precious opportunity.
_Ord._ _Ord_, order, arrangement.
_O’Regan._ _O_, descendant; _Regan_, from _riǵ_, a king; _an_ for _tan_,
place, region. Descendant of Regan.
_O’Reilly._ _Ua Raǵallać_, from _ua_, grandson, _riaǵail_, a rule;
_ać_, an individual. Descendant of a ruler; grandson of a king.
_O’Rourk._ _Ua Ruarcać_, from _ua_, descendant; _rad́arc_, pronounced in
Connaught _rooarc_, sight, and _ać_, an individual. Grandson of Rourk;
descendant of a man of judgment. O’Rourke, O’Rorke, kindred names.
_Orr._ _Or_, gold, wealth, riches. In a secondary sense, precious,
valuable.
_O’Shaughnessy._ _O_, descendant; _Seaǵan_, pronounced _Shaughn_,
or _Shawn_, genitive _Seaǵain_, John; _nees_, _ni_, daughter, and
Anglo-Saxon _s_ for _sun_, son; _y_ for _eać_, an individual. Grandson of
a person belonging to the son of the daughter of John. O’Shannessy, of
like derivation.
_O’Shanter._ _O_, descendant; _Seaǵain_, John’s; _ter_, from _tir_,
country. A descendant of John’s country.
_Ossian._ _Osna_, a sigh; _n_ for _an_, denoting a personal noun. One who
sighs; a mourner.
_O’Sullivan._ _O_, descendant; _suile_, pronounced _soo-il_, genitive of
_suil_, the eye; _i_ for _a_, his; _b́ean_, woman.
_O’Toole._ _O_, descendant; genitive _tuile_, pronounced _too-il_, of
flood. Descendant of a flood.
_Owen._ _Eon_, perhaps from _uan_, pronounced _oo-an_, a lamb. From _Mac
Eoin_, son of Owen, have arisen MacKeon, Keon, Coyne, Owens, and Owenson.
_Owenson._ _Owen_, and _sun_, the Anglo-Saxon of son. Son of Owen. Owens
is the same name curtailed of the last two letters.
_O’Weir._ _O_, descendant; Anglo-Saxon _wér_, a man, Irish genitive
_weir_. Descendant of man.