O
noun
the fifteenth letter of the English alphabet, a vowel.
Jump To:
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O
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o'
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O'
O'a prefix meaning “descendant,” in Irish family names.
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o-
o-an abridgment of ortho-.
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-o
-oa suffix occurring as the final element in informal shortenings of nouns (ammo; combo; condo; limo; promo ); -o also forms nouns, usually derogatory, for persons or things exemplifying or associated with that specified by the base noun or adjective (cheapo; pinko; sicko; weirdo; wino ).
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o.
o.abbreviationpint.
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-o-
-o-the typical ending of the first element of compounds of Greek origin (as -i- is, in compounds of Latin origin), used regularly in forming new compounds with elements of Greek origin and often used in English as a connective irrespective of etymology.
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O.
O.abbreviation(in prescriptions) a pint.
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o
onounthe 15th letter and fourth vowel of the modern English alphabet
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O'-
O'-prefix(in surnames of Irish Gaelic origin) descendant of
O
1 American
[oh]
/ oʊ /
Or
o
noun
O's,
plural
Os,
plural
o's,
plural
os,
plural
oes
plural
-
the fifteenth letter of the English alphabet, a vowel.
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any spoken sound represented by the letter O or o, as in box, note, short, or love .
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something having the shape of an O .
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a written or printed representation of the letter O or o.
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a device, as a printer's type, for reproducing the letter O or o.
O
2
American
[oh]
/ oʊ /
interjection
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(used before a name in direct address, especially in solemn or poetic language, to lend earnestness to an appeal).
Hear, O Israel!
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(used as an expression of surprise, pain, annoyance, longing, gladness, etc.)
noun
O's
plural
O
3
American
O
4
American
Symbol.
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the fifteenth in order or in a series.
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the Arabic cipher; zero.
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(sometimes lowercase) the medieval Roman numeral for 11.
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Physiology. a major blood group, usually enabling a person whose blood is of this type to donate blood to persons of group O, A, B, or AB and to receive blood from persons of group O.
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Chemistry. oxygen.
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Logic. particular negative.
o'
5
American
[uh, oh]
/ ə, oʊ /
O'
6
American
o-
7
American
Chemistry.
o-
8
American
o-
9
American
-o
10
American
-
a suffix occurring as the final element in informal shortenings of nouns (ammo; combo; condo; limo; promo ); -o also forms nouns, usually derogatory, for persons or things exemplifying or associated with that specified by the base noun or adjective (cheapo; pinko; sicko; weirdo; wino ).
-
a suffix occurring in colloquial noun or adjective derivatives, usually grammatically isolated, as in address.
cheerio; kiddo; neato; righto.
o.
11
American
abbreviation
o.
12
American
abbreviation
-
octavo.
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off.
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old.
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only.
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order.
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Baseball. out; outs.
-o-
13
American
O.
14
American
abbreviation
O.
15
American
abbreviation
-
Ocean.
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octavo.
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October.
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Ohio.
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Old.
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Ontario.
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Oregon.
O
1
British
symbol
-
chem oxygen
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a human blood type of the ABO group See universal donor
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logic a particular negative categorial proposition, such as some men are not married: often symbolized as SoP Compare A E I 2
abbreviation
o
2
British
/ əʊ /
noun
-
the 15th letter and fourth vowel of the modern English alphabet
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any of several speech sounds represented by this letter, in English as in code, pot, cow, move, or form
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another name for nought
O
3
British
/ əʊ /
interjection
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a variant spelling of oh
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an exclamation introducing an invocation, entreaty, wish, etc
O God!
O for the wings of a dove!
O'-
4
British
prefix
-o
5
British
suffix
-o-
6
British
o-
7
British
prefix
o'
8
British
/ ə /
preposition
Other Word Forms
Noun Inflected Forms
Etymology
Origin of O2
First recorded in 1125–75; Middle English, from Old French, from Latin ō
Origin of o'5
From Middle English; by shortening
Origin of O'6
Representing Irish ó descendant, Old Irish au
Origin of -o10
Perhaps originally the interjection O, appended to words as in -o def. 2; as a derivational suffix reinforced by clipped forms of words with -o- as a linking element (e.g., photo, stereo ), by Rom nouns ending in o, and by personal nouns such as bimbo and bozo, of obscure origin
Origin of o.11
From the Latin word octārius
Origin of -o-13
Middle English (< Old French ) < Latin < Greek
Origin of O.14
From the Latin word octārius
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
See Examples For:
Among those scheduled to perform are Beck, Jenny Lewis, Karen O, Rufus Wainwright and Devo, among many more.
From Los Angeles Times ● Jul. 8, 2026
“Coach O understands my expectations and commitment to being a championship program,” Kiffin said.
From Los Angeles Times ● May 21, 2026
Since January, only one shipment of Russian crude has reached Cuban ports, and the fuel refined from it has already been used, De la O said.
From The Wall Street Journal ● May 14, 2026
Kanayo O Kanayo described his outfit as "ripping in godfatherism, old money and tailored mafia".
From BBC ● May 10, 2026
“I tell you, O Queen,” the messenger said, “I was there and the thing happened thus. Clearly your child has been borne away to the gods.”
From "Mythology: Timeless Tales of Gods and Heroes" by Edith Hamilton
“Coffee badging”—going to the office just long enough to show your face and grab a cup o’ joe—was a popular workaround.
From The Wall Street Journal ● Dec. 30, 2025
Amelie McCann said Julia Wandelt had told her she had memories of playing Ring a Ring o' Roses with her and feeding her brother Sean.
From BBC ● Oct. 9, 2025
These sea snails are also voracious predators themselves and feast upon free-floating hydrozoan such as Velella velella and Portuguese man o’ war.
From Los Angeles Times ● Jul. 23, 2025
Any way you slice it, this week’s Slate News Quiz is a piece o’ fun.
From Slate ● Nov. 1, 2024
Long as they’ve got a couple o’ hundred humans stuck there with ’em, so they can leech all the happiness out of ’em, they don’ give a damn who’s guilty an’ who’s not.”
From "Harry Potter And The Prisoner Of Azkaban" by J.K. Rowling
Former basketball player Shaquille O’ Neal is also a high-profile investor.
From MarketWatch ● Nov. 19, 2025
The castle, near John O' Groats, is the most northerly inhabited castle in Scotland and the property and its gardens are run as a visitor attraction in summer months.
From BBC ● Oct. 27, 2025
But Heart O’ the Hills confirmed that its camp director, Jane Ragsdale, is one of the flood’s victims .
From Salon ● Jul. 7, 2025
Girls summer camp Heart O’ the Hills is just a mile north of Camp Mystic.
From Salon ● Jul. 7, 2025
After a single trip to the supermarket, the refrigerator and the cupboards fill with familiar labels: Skippy, Hood, Bumble Bee, Land O’ Lakes.
From "The Namesake" by Jhumpa Lahiri
At week's end a Russian delegation got the signatures of the leaders of Kazakhstan on a similar agreement-to-try-t o- agree.
From Time Magazine Archive
The text of the larger o- fuda is often accompanied by curious pictures or symbolic illustrations.
From In Ghostly Japan by Hearn, Lafcadio
The soft, long-drawn "o- ohs!" that came to his ears were full of a music that made him impervious to pain.
From Green Fancy by McCutcheon, George Barr
And trewelie, if there be any // and in no o- good in them, it is either lerned, borowed, or // ther tong. stolne, from some one of those worthie wittes of Athens.
From The Schoolmaster by Ascham, Roger
In the absence of free sulphuric acid the conversion of o- into p-phenolsulphonic acid is brought about by heating the aqueous solution.
From Synthetic Tannins by Grasser, Georg
Usually words ending in "-o" are masculine and those ending in "-a" are feminine, but there are many common words that break those gender rules, like "la mano," the word for "hand."
From Salon ● Sep. 26, 2022
I don't think the "-e" should eliminate the existing "-o" and the "-a."
From Salon ● Sep. 26, 2022
The -o suffix traces back to old comic strip characters with names like Knocko and Groucho.
From Slate ● Mar. 31, 2020
Knocko, Peddlo, Henpecko, and the rest became so popular that the -o suffix soon spread to words up and down the English language.
From Slate ● Mar. 31, 2020
I knew perfectly well why, but I didn’t know how -o put it.
From "Boy: Tales of a Childhood" by Roald Dahl
Collated tables for all molecular evolution measures for all genes can be found in Source Data File 1 for P. malariae and P. o. curtisi.
From Nature ● Jan. 24, 2017
The P. o. wallikeri and the P. o. curtisi chromosomes were aligned against each other, as were the P. malariae and P. malariae-like chromosomes.
From Nature ● Jan. 24, 2017
Reality is that you are giving up your family time by doing the o. t. when they need you at work.
From Time ● May 3, 2013
“If you dey come give am ticket to leave this here country, I will disappear o. I will not even stop home for pick my bag.”
From Washington Post
“Yes o. Are you the person that will marry me? Meanwhile I told Don I am going out with you, so make sure you don’t go anywhere that he might go.”
From "Americanah" by Chimamanda Ngozi Adichie
Thus masc. -o- stems show palatal modification, e.g. corn, “horn,” plur. cyrn < *kornī; the plural ending of -u- stems, O. Gaulish -oves, gives O.W. -ou, Mid.
From Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 5 "Cat" to "Celt" by Various
And if he’s going to be a senator, he says, he needs to lock down a Jackie O. – not a Marilyn.
From Salon ● Jul. 6, 2026
District Court Judge David O. Carter ordered the VA to build 2,500 units in addition to the 1,200 the agency agreed to build to settle the earlier case.
From Los Angeles Times ● Jun. 10, 2026
The one here involves the eight pits that were unearthed 40 years ago by workers in Sanxingdui in southern China “at the foot of the Tibetan mountains,” as narrator Jay O. Sanders tells us.
From The Wall Street Journal ● May 26, 2026
Anna O. Law: The biggest myth about American immigration is that until the federal government started enforcing our borders in the late 19th century, it was just open borders.
From Slate ● Mar. 16, 2026
“You do that for a couple weeks and you get dank,” said de la O. “It gets to you after a while.”
From "Boots on the Ground: America's War in Vietnam" by Elizabeth Partridge
Welsh folk singer Dafydd Iwan says he has received "very personal" and "nasty" comments after urging organisers of a right-wing protest to stop using his song Yma o Hyd.
From BBC ● Feb. 1, 2026
Mr. Brownlee’s tenor proved rock-solid in Arturo’s demanding music, from his exquisitely relaxed, almost languid opening aria, “A te, o cara,” to some punishing high Fs.
From The Wall Street Journal ● Jan. 2, 2026
Shares o Carvana were down 7.9% in after-hours trading following the release.
From Barron's ● Oct. 29, 2025
It was a deep sleep, and I didn’t wake up until morning. o o o It is an upcar tearing along over the desert.
From "Feed" by M.T. Anderson
Fearing that Hindu-Arabic numerals—the o through 9 used today—would promote confusion and fraud, some European authorities banned them until the fourteenth century.
From "1491" by Charles C. Mann
While some winning coaches were making their names with toughness that bordered on abuse, he urged Close to see her teams as human beings first, not X’s and O’s.
From The Wall Street Journal ● Apr. 6, 2026
Certainly, I think given the amount of pastry I consume and have consumed in my lifetime, I thought that Mary O’s Irish Soda Bread scones were kind of a revelation.
From Los Angeles Times ● Oct. 3, 2025
Which raises the obvious question - if the prosecution were wrong about Baby O's liver injuries, then why did he die?
From BBC ● Aug. 11, 2025
The prosecution pathologist concluded that there was no evidence that a needle had pierced Baby O's liver while he was alive and the paediatric pathologist we spoke to agrees.
From BBC ● Aug. 11, 2025
The babies’ lips pursed into two round O’s.
From "The Long-Lost Home" by Maryrose Wood
"The Dutch experience in my opinion offers a warning for Canada," Os cautioned.
From BBC ● May 15, 2026
Since then, Os has come to rule the Latin pop scene in Mexico, boasting multiple sold-out tours of the country.
From Los Angeles Times ● Mar. 20, 2026
On the personal side, Os is also relishing her relationship with Peso Pluma.
From Los Angeles Times ● Mar. 20, 2026
Os achieved an international breakthrough with her visual album, 2022’s “K23.”
From Los Angeles Times ● Mar. 20, 2026
She’d been fourteen, and her family had been summering on the coast of West Ravka, enjoying the seaside and performing in a carnival on the outskirts of Os Kervo.
From "Six of Crows" by Leigh Bardugo
Like other Romance languages, Spanish divides most endings of nouns into masculine o’s or feminine a’s.
From Washington Times ● Dec. 12, 2021
Texting and Millennials The phone holds a million x’s and o’s.
From Forbes ● Jun. 5, 2013
Actual coaching — x’s and o’s — would become more important.
From New York Times ● Dec. 30, 2011
A young executive named Mark Shapiro, now gone, pushed it as a way to broaden the network's appeal beyond "the hard x's and o's crowd."
From Slate ● Jun. 1, 2011
Since the censors’ Greek was even worse than Milton’s, they often made mistakes, lopping off endearments, x’s and o’s.
From "Middlesex: A Novel" by Jeffrey Eugenides
Dreyfus pleased his friends no better than his :oes: he irked them by not becoming a "Dreyfusard."
From Time Magazine Archive
The poet "mouthing out his hollow oes and aes" is, we are told, a good description of Tennyson's tone and manner of reading.
From The Early Poems of Alfred Lord Tennyson by Collins, John Churton
Cymmrodedd fy llyw lluoedd beri, Nid oes rwyf eirioes, aer dyfysgu, Cymro yw haelryw o hil Beli hir, Yn herwydd i brofi.
From Some Specimens of the Poetry of the Ancient Welsh Bards by Evans, Evan
And from the shadow one by one Pick up the playful oes of sun?
From The Poetical Works of Robert Bridges by Bridges, Robert
A new Longevity Preparedness Index from John Hancock and MIT AgeLab os based on a survey of over 1,300 adults and focused on eight areas such as finance, home, health and community.
From MarketWatch ● Dec. 12, 2025
She first broke through with 2016’s “Remonta,” an album she recorded with her former band Liniker e os Caramelows.
From Los Angeles Times ● Oct. 8, 2025
Newton disliked infinitesimals, the little os in his fluxion equations that sometimes acted like zeros and sometimes like nonzero numbers.
From "Zero: The Biography of a Dangerous Idea" by Charles Seife
The os in his calculations were only intermediaries, crutches that vanished miraculously by the end of the computation.
From "Zero: The Biography of a Dangerous Idea" by Charles Seife
In the 19 3 os, track experts were beginning to toss around the idea of a four-minute mile.
From "Unbroken" by Laura Hillenbrand
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
