O
noun
the fifteenth letter of the English alphabet, a vowel.
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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
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O's,
plural
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Os,
plural
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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
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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
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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
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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:
The MAL story also illustrates how much complexity is hidden behind the familiar letters A, B, AB and O.
From Science Daily ● Sep. 19, 2026
“No doubt about it... You cannot understand the power of the O factor,” he said.
From Los Angeles Times ● Aug. 14, 2026
Up until the Big O, I’ve lived by that rule.
From The Wall Street Journal ● Aug. 7, 2026
Bennett has reviewed one case, referred to in court as Baby O, in detail on behalf of her new defence.
From BBC ● Jul. 22, 2026
The four of us crowded into the O and threw our arms around each other.
From "Maybe He Just Likes You" by Barbara Dee
“But also look at a Prince album like Sign o’ the Times, which is a masterpiece, but some of Prince’s best ideas on that album are mistakes.”
From The Wall Street Journal ● Oct. 22, 2026
The third, on “I’m Doun for Lack o’ Johnnie,” is the emotional focal point of the Fantasy, a lament both intimate and universal.
From The Wall Street Journal ● Oct. 16, 2026
Although their sting is generally considered "very mild" in comparison to Portuguese man o' war, Hobro advised people not to touch them.
From BBC ● Jun. 18, 2026
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
The title of the book was East o’ the Sun and West o’ the Moon.
From "Bad Boy" by Walter Dean Myers
Former basketball player Shaquille O’ Neal is also a high-profile investor.
From MarketWatch ● Nov. 19, 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
The 55-year-old, who is also known as Thomas O'Brien or Tam O' Braan, rented a former sheep farm near Loch Tay and began spinning "elaborate lies" to customers.
From BBC ● May 29, 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
Toluene treated with fuming sulphuric acid first yields o- and p-sulphonic acids, finally o- and p-disulphonic acids, ethylbenzene at the boiling point p-ethylbenzene-sulphonic acid.
From Synthetic Tannins by Georg Grasser
The text of the larger o- fuda is often accompanied by curious pictures or symbolic illustrations.
From In Ghostly Japan by Lafcadio Hearn
Quintilianus saieth, that Ethopœia is a imitacion of o- ther meane maners: whom the Grekes dooe calle, not onelie Ethopœia, but mimesis, & this is in the maners, and the fact.
From A booke called the Foundacion of Rhetorike because all other partes of Rhetorike are grounded thereupon, euery parte sette forthe in an Oracion vpon questions, verie profitable to bee knowen and redde by Richard Rainolde
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 Georg Grasser
I don't think the "-e" should eliminate the existing "-o" and the "-a."
From Salon ● Sep. 26, 2022
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
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
The -o suffix traces back to old comic strip characters with names like Knocko and Groucho.
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
The Illumina-based genome assemblies for P. o. curtisi, P. o. wallikeri, and P. malariae-like were performed using MaSURCA30 for samples PocGH01, PowCR01, and PmlGA01 respectively.
From Nature ● Jan. 24, 2017
As a Gene Ontology database, the predicted Gene Ontology terms from the P. falciparum 3D7 genes orthologous to the P. malariae and P. o. curtisi genes included in the analysis were used.
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
“Me, I want as many governors as possible to come to my own wedding o. It shows levels, serious levels,” Ranyinudo said.
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
District Judge David O. Carter issued a preliminary injunction, calling HUD’s action arbitrary and capricious.
From Los Angeles Times ● Sep. 4, 2026
Thankfully, Curry did not allow any eerie rumors to deter him from securing the home, which was originally built in 1922, having been designed by acclaimed architect Stiles O. Clements.
From MarketWatch ● Aug. 31, 2026
“Gerald J. Ford has significant memory problems,” Jeremy Ford wrote, reiterating his allegations Kelli O. Ford was attempting to block him from seeing his father.
From The Wall Street Journal ● Aug. 30, 2026
The Senate opened debate this week on the late South Carolina senator’s legacy legislation—the Lindsey O. Graham Sanctioning Russia and Iran Act—by an overwhelming 86–12 vote.
From Slate ● Aug. 1, 2026
“But you do not come home on the P. & O. boat?”
From "Murder on the Orient Express" by Agatha Christie
“LAHD is very excited about the opportunities ...t o produce more affordable housing and stabilize the city’s housing stock,” said Tiena Johnson Hall, the housing department’s general manager.
From Los Angeles Times ● Sep. 23, 2026
Allow me to sing, o Muse, of a recent dinner conversation about “The Odyssey.”
From Salon ● Aug. 2, 2026
But the legs that underpin the stool of Wall Street’s still-bullish forecasts, in the form of Fed rate cuts, slowing inflation pressures, and a resilient economy, have started o wobble.
From Barron's ● Mar. 19, 2026
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
"But am and o are separate clues," Flora Baumbach said.
From "The Westing Game" by Ellen Raskin
Barely a week after tying the knot with Taylor Swift in July, Kansas City Chiefs tight end Travis Kelce was back at work inside Johnny O’s Gymnasium in Florida.
From The Wall Street Journal ● Sep. 30, 2026
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
Does the olfactory exhilaration also enhance play-calling, amplifying one’s grasp of X’s and O’s?
From Los Angeles Times ● Jan. 12, 2026
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
Finally de la O’s dad landed a full-time job in a meat-packing factory in Saint Paul, Minnesota.
From "Boots on the Ground: America's War in Vietnam" by Elizabeth Partridge
In 1988, he founded Luaka Bop, a record label whose influential compilations have introduced American audiences to lesser-known classics of world pop and psychedelia, such as Brazil’s Os Mutantes.
From The Wall Street Journal ● Oct. 9, 2026
"The Dutch experience in my opinion offers a warning for Canada," Os cautioned.
From BBC ● May 15, 2026
Os had plenty of examples of powerful pop divas to draw inspiration from.
From Los Angeles Times ● Mar. 20, 2026
Another hurdle that Os had to overcome in her career is an ongoing stigma placed on influencers-turned-pop stars.
From Los Angeles Times ● Mar. 20, 2026
Some Os and Qs and Cs long and narrow.
From "One Crazy Summer" by Rita Williams-Garcia
Like other Romance languages, Spanish divides most endings of nouns into masculine o’s or feminine a’s.
From Washington Times ● Dec. 12, 2021
Twitter’s closed captioning wrote it out twice, with each ¡Gol! featuring 27 o’s.
From Slate ● Jun. 17, 2018
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
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 John Churton Collins
Yr un peth a ellir ei ddywedyd am Daliesin Ben Beirdd, nid oes neb heddyw, hyd i gwn i, a fedr gyfieithu yn iawn un o’i Awdlau na’i Orchanau.
From Some Specimens of the Poetry of the Ancient Welsh Bards by Evan Evans
And from the shadow one by one Pick up the playful oes of sun?
From The Poetical Works of Robert Bridges by Robert Bridges
However thick-skinned a man may be, and protected over all by the oes triplex of self-sufficiency, he cannot escape being wounded by furious and incessant attacks.
From The Atlantic Monthly, Volume 04, No. 21, July, 1859 by Various
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
Ambos os programas são “fundamentais para entender a expansão agrícola no Brasil e as emissões de carbono do desmatamento na Amazônia,” diz Douglas Morton, especialista em sensoriamento remoto do Goddard Space Flight Center da NASA.
From Science Magazine ● May 26, 2022
Hours later, Kelly posts bail and os released from jail in Chicago.
From Seattle Times ● Aug. 18, 2021
You could talk to him about os and argos, suet and grease, croteys, fewmets and fiants, but he only looked polite.
From "The Once and Future King" by T. H. White
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