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
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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
The fest will feature a star-studded, all-women lineup including Rodrigo, Chappell Roan, Mitski, Doechii and special guests Karen O, Sarah McLachlan and Stevie Nicks.
From Los Angeles Times ● Aug. 28, 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
Dr Labhrás O Murchú from CCÉ said the event was "unprecedented".
From BBC ● Aug. 10, 2026
It is a fast and festive song, with a repeated line that’s almost shouted: O, bella, ciao!
From "A Heart in a Body in the World" by Deb Caletti
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
Similar to Portuguese man o' war, by-the-wind sailors are colonies of animals related to sea anemones and corals, and they possess stinging cells.
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
“He’ll be glad o’ sensible company, he will, alone in that castle with them young rascals from Glasgow.”
From "Code Name Verity" by Elizabeth Wein
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
Phenol-2,4-disulphonic acid is prepared from o- or p-phenolsulphonic acid, whereas phenol-2,4,6-trisulphonic acid is prepared directly from phenol by heating with concentrated sulphuric acid in presence of phosphorus pentoxide.
From Synthetic Tannins by Georg Grasser
Of the three isomeric xylenes o- and m-xylene dissolve in concentrated, p-xylene in fuming sulphuric acid only.
From Synthetic Tannins by Georg Grasser
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
Similarly, condensation of different samples of crude cresol containing varying quantities of o-, m-, and p-cresol did not yield end-products sufficiently different to justify describing them in detail.
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
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
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
If Justice Thomas remains on the court another 19 months, he will surpass William O. Douglas as the longest-serving justice in history.
From The Wall Street Journal ● Sep. 29, 2026
District Court Judge David O. Carter ordered the VA to build about 2,500 units of temporary and permanent housing in addition to the 1,200 required in the earlier lawsuit.
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
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
He removed a wallet from his back pocket, demonstrating to O. J. Martinez that it was empty.
From "The Milagro Beanfield War" by John Nichols
“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
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
“The traders say it is hard to transport their food because there is no fuel, so they add on the costs of transportation, o di egivu,” Aunty Ifeoma said.
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
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
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
Carson Palmer’s coaching staff, filled with former NFL players like himself, have shown they can teach, lead and handle X’s and O’s.
From Los Angeles Times ● Nov. 23, 2025
“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
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
Os has even accompanied Pluma on a few stops of his recent Dinastía Tour.
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
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
Speaking in the same New Orleans twang as her students—those bouncy o’s and long, lingering a’s—Foster was teaching her fifth-graders about chemical reactions.
From Slate ● Jun. 5, 2016
Texting and Millennials The phone holds a million x’s and o’s.
From Forbes ● Jun. 5, 2013
“Because, see, we’re in Spanish class with all the a's and o’s at the end, and Troy just comes up with this name, Ema, just like that, and boom, it stuck. You see?”
From "Shelter (Book One): A Mickey Bolitar Novel" by Harlan Coben
Dreyfus pleased his friends no better than his :oes: he irked them by not becoming a "Dreyfusard."
From Time Magazine Archive
Dreig Arfon arfod wythlonedd Dragon diheufeirch heirddfeirch harddedd, Ni chaiff Sais i drais y droedfedd oi fro, Nid oes o Gymro i Gymrodedd.
From Some Specimens of the Poetry of the Ancient Welsh Bards by Evan Evans
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
Dywedir mai enw y gwas oedd Dafydd Hiraddug, ac iddo werthu ei hun i’r diafol, ac oherwydd hyny, ei fod yn alluog i gyflawni gweithredoedd anhygoel yn yr oes hon.
From Welsh Folk-Lore a Collection of the Folk-Tales and Legends of North Wales by Elias Owen
And from the shadow one by one Pick up the playful oes of sun?
From The Poetical Works of Robert Bridges by Robert Bridges
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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