O is the fifteenth letter of the modern Latin alphabet. O may also refer to:

Letters

* Օ օ, (Unicode: U+0555, U+0585) a letter in the Armenian alphabet * Ο ο, Omicron, (Greek), a letter in the Greek alphabet * O (Cyrillic), a letter of the Cyrillic alphabet * O (kana), a romanization of the kana (お and オ) in Japanese writing *

ㅇ ㅇ( ko, 이응, ieung) is a consonant letter of the Korean alphabet, Hangul. The Unicode for ㅇ is U+3147. It is silent when used at the beginning of a syllable (it is a consonant placeholder in vowel A vowel is a syllabic speech sound pro ...

, a consonant in Hangul, the Korean alphabet *

ဝ The Burmese alphabet ( my, မြန်မာအက္ခရာ ''mranma akkha.ra'', ) is an abugida used for writing Burmese language, Burmese. It is ultimately adapted from a Brahmic scripts, Brahmic script, either the Kadamba alphabet, Kada ...

, a consonant in Burmese script * /o/, close-mid back rounded vowel in the International Phonetic Alphabet Vo (letter)

Arts and entertainment

Film and television

* ''O'' (film), 2001 film starring Josh Hartnett, Mekhi Phifer and Julia Stiles

Literature

* '' O: A Presidential Novel'', anonymous novel published in 2011 * O, fictional planet that is the setting of several short stories by science fiction author Ursula K. Le Guin * O, fictional character from the French erotic novel ''

Story of O ''Story of O'' (french: Histoire d'O, link=no, ) is an erotic novel published in 1954 by French author Anne Desclos under the pen name Pauline Réage, and published in French by Jean-Jacques Pauvert. Desclos did not reveal herself as the autho ...

'' * ''

"O" Is for Outlaw ''"O" Is for Outlaw'' is the 15th novel in Sue Grafton's "Alphabet" series of mystery novels and features Kinsey Millhone, a private eye based in Santa Teresa, California. The novel's plot has its roots in the Vietnam War, and features informati ...

'', the fifteenth novel in Sue Grafton's "Alphabet mystery" series, published in 1999

Media and publications

* '' O, The Oprah Magazine'', magazine founded by Oprah Winfrey * '' «O»'', an international fetish magazine

Music

* " O (Oh!)", 1920 by Ted Lewis, 1953 by Pee Wee Hunt * ''O'' (A.C. Acoustics album), 2002 * ''O'' (Damien Rice album), 2002 * ''O'' (Eiko Shimamiya album), 2006 * ''O'' (Omarion album), 2005 ** "O" (Omarion song), the title song * ''o'' (Tilly and the Wall album), 2008 * ''O'', 2002 album by Zone * "O", a 2014 song by Coldplay from '' Ghost Stories'' * "o", a song by iamamiwhoami * "O!", a song by the American band Bright from '' The Albatross Guest House'', 1997

Sports

* O (gesture), a gesture used to show support for the sports teams of the University of Oregon * Baltimore Orioles, an American Major League Baseball team, among whose common nicknames are "O's" and "The O's"

Others

* ''O'' (Cirque du Soleil), show at the Bellagio hotel and casino in Las Vegas, Nevada

Companies

* Essie's Original Hot Dog shop (commonly known as "The O"), a restaurant in Pittsburgh, Pennsylvania * Overstock.com, online retailer previously known as O.co * Realty Income, American real estate investment trust (NYSE stock ticker O)

History

* O-class battlecruiser, class of German ships in the 1930s * The O (political group) (The Organization), a 1970s American political group

Linguistics

* O, an antiquated vocative placed before a name of, or phrase characterizing, the party being addressed * O (also P), the patient-like argument (object) of a canonical transitive verb *O, gender neutral third person pronoun in the Turkish language

Mathematics

f = O(g)

, a Bachmann–Landau notation in computational complexity theory (", ''f'', is bounded above by ''g'' asymptotically") *

f = o(g)

, a Bachmann–Landau notation in computational complexity theory ("''f'' is dominated by ''g'' asymptotically") * O, for

orthogonal group In mathematics, the orthogonal group in dimension , denoted , is the Group (mathematics), group of isometry, distance-preserving transformations of a Euclidean space of dimension that preserve a fixed point, where the group operation is given by ...

* ∘ indicates

function composition In mathematics, function composition is an operation that takes two functions and , and produces a function such that . In this operation, the function is applied to the result of applying the function to . That is, the functions and ...

, or composition of morphisms in a category * Category O or

\mathcal

, a category of Lie algebra representations * o, for octet, an information measure unit used in computing

Media

* O, an IRC operator service in QuakeNet's IRC services

Places

* O Brook, a short river in Devon, England

Science

* Oxygen, symbol O, a chemical element * O, a human

blood type A blood type (also known as a blood group) is a classification of blood, based on the presence and absence of antibodies and inherited antigenic substances on the surface of red blood cells (RBCs). These antigens may be proteins, carbohydrate ...

, the universal donor * Haplogroup O (Y-DNA), a Y-chromosomal DNA haplogroup * O, for

pyrrolysine Pyrrolysine (symbol Pyl or O; encoded by the 'amber' stop codon UAG) is an α-amino acid that is used in the biosynthesis of proteins in some methanogenic archaea and bacteria; it is not present in humans. It contains an α-amino group (which is ...

an alpha amino acid in biochemistry * Class O, stellar classification for very hot bluish stars * O (for ''Octavius'', meaning an eight of a gallon), an apothecary's symbol for a pint

Surname

* O (surname), Korean surname romanized "O" or "Oh" * Ō (Japanese surname), Japanese surname derived from the Chinese surname Wang (王) * Ou (surname), Chinese and Cantonese surnames pronounced "O" or "Oh" * A prefix meaning "grandson (of)", appearing in Irish surnames * Genovevo de la O (1876-1952), Mexican revolutionary * Karen O, born Karen Lee Orzolek, American singer

Other uses

* Oreo O's, an American breakfast cereal available internationally * Oscar, the military time zone code for UTC−02:00: List of military time zones#O