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
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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 ).
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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
It offers a sports-themed way of approaching the topic, called GOALS, representing G: get ready; O: open the conversation; A: ask the question; L: listen and respond and S: support and signpost.
From BBC ● Sep. 9, 2026
A delicious word salad: How many words can you create with the letters Y, B, O, F, U, and N?
From Slate ● Aug. 18, 2026
It also gives non-Asian chorus members a reason to be present at Butterfly’s wedding, though having a group of American ladies sing the invocation “O Kami! O Kami!” from song sheets seemed peculiar.
From The Wall Street Journal ● Aug. 17, 2026
"We understand, O Brainy One!" cried the audience.
From "The Witches" by Roald Dahl
“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
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
“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
I was raised about two blocks from where you lived at the time, near Tail o’ the Pup.
From Los Angeles Times ● Jan. 22, 2025
‘A present from Sméagol,’ said Sam: ‘a brace o’ young coneys; though I fancy Gollum’s regretting them now.
From "The Two Towers" by J. R. R. Tolkien
Former Nasa administrator Sean O' Keefe told the BBC that the nations that land on the Moon will have the advantage of exploring and developing the resources that are there.
From BBC ● Mar. 31, 2026
Visitor access to nearby Man O' War beach remains open.
From BBC ● Feb. 24, 2026
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
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
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
The text of the larger o- fuda is often accompanied by curious pictures or symbolic illustrations.
From In Ghostly Japan by Lafcadio Hearn
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 George Barr McCutcheon
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
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
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
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
This gene family was recently named KELT7, and we confirm the 8 copies present in P. o. wallikeri, but show that P. o. curtisi has 9 copies, two of which are pseudogenes.
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
District Judge David O. Carter to quickly schedule status conference to set a compliance timetable for the government.
From Los Angeles Times ● Sep. 11, 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
My mouth made a little round O. “If I run into her, I will,” I stammered finally.
From "The Lions of Little Rock" by Kristin Levine
“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
"The lack of justice has sparked this wave of protests," Abu Ahmed Faijul Kabir of the legal rights group Ain o Salish Kendra told AFP.
From Barron's ● May 22, 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
“Amaka, o gini? I don’t like that tone!”
From "Purple Hibiscus" by Chimamanda Ngozi Adichie
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
“He doesn’t have a body that you would be like, ‘Wow, this guy’s a specimen,’” said Johnny Olson, the owner of Johnny O’s.
From The Wall Street Journal ● Sep. 30, 2026
Both senior managers were subsequently disciplined by Google for witnessing Mr O's conduct and failing to intervene, before later being made redundant.
From BBC ● Mar. 10, 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
“I knows what them is,” he said, putting his finger on the X’s and O’s.
From "Code Talker: A Novel About the Navajo Marines of World War Two" by Joseph Bruchac
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 has even accompanied Pluma on a few stops of his recent Dinastía Tour.
From Los Angeles Times ● Mar. 20, 2026
Last year, Os also pulled a page from Taylor Swift’s playbook by releasing the concert film “Kenia Os: La OG” in theaters in both the U.S. and Mexico.
From Los Angeles Times ● Mar. 20, 2026
The Gs in her name looked like nibbled Os.
From "Inkheart" by Cornelia Funke
They eventually named their institute for an online trend that had slime enthusiasts replacing the vowels in their name with double o’s, so Kira would become “Kooroo” and slime becomes “Sloomoo.”
From Washington Post ● Jun. 30, 2022
Like other Romance languages, Spanish divides most endings of nouns into masculine o’s or feminine a’s.
From Washington Times ● Dec. 12, 2021
Mathematics said that any concept could be conveyed in such a binary code as long as the sequence of i’s and o’s was long enough.
From Forbes ● Sep. 2, 2014
Actual coaching — x’s and o’s — would become more important.
From New York Times ● Dec. 30, 2011
It was almost perfect, just a fraction flatter and shakier than Betty Jean’s voice had been, the o’s and ah’s parodies of Betty Jean’s pretentious ones.
From "Jacob Have I Loved" by Katherine Paterson
Dreyfus pleased his friends no better than his :oes: he irked them by not becoming a "Dreyfusard."
From Time Magazine Archive
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
Ir wyfi yn meddwl nad oes neb a ryfygei gymmeryd y fath orchest arno.
From Some Specimens of the Poetry of the Ancient Welsh Bards by Evan Evans
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
The colors that show best by candle-light are white, carnation, and a kind of sea-water-green; and oes, or spangs, as they are of no great cost, so they are of most glory.
From The Essays of Francis Bacon by Francis Bacon
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
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
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