O (disambiguation)

Media and publications

• O, The Oprah Magazine, magazine founded by Oprah Winfrey
• O (German magazine), a 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 (Oval album), 2010
• o (Tilly and the Wall album), 2008
• O (EP), a 2023 EP by Yuju
• 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
• O (musician), nickname of the American musician Otis Barthoulameu
• A Band Called O

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/, close-mid back rounded vowel in the International Phonetic Alphabet
• 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
• O-, an honorific prefix used in the Japanese language

Mathematics

• , a Bachmann–Landau notation in computational complexity theory ("|f| is bounded above by g asymptotically")
• , a Bachmann–Landau notation in computational complexity theory ("f is dominated by g asymptotically")
• O, for orthogonal group
• ∘ indicates function composition, or composition of morphisms in a category
• Category O or , a category of Lie algebra representations
• o, for octet, an information measure unit used in computing
• Kleene's O, a system of ordinal notations

Media

• O, an IRC operator service in QuakeNet's IRC services
• O Channel, the former name of Moji a television network in Indonesia

Places

• O Brook, a short river in Devon, England
• O'Block, a colloquial name for the Parkway Garden Homes in Chicago

Science

• Oxygen, symbol O, a chemical element
• O, a human blood type, the universal donor
• Haplogroup O (Y-DNA), a Y-chromosomal DNA haplogroup
• O, for pyrrolysine an alpha amino acid in biochemistry
• O-type star, stellar classification for very hot bluish stars
• O (for Octavius, meaning an eighth 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)
• Ō clan a historical Japanese clan with an unrelated surname
• 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
• , the official West Japan Railway Company service symbol for the Osaka Loop Line

See also

• Mr. O (TV show)
• Circle (disambiguation)
• Circle symbol (disambiguation)
• Zero (disambiguation)
• Big O (disambiguation)
• Omicron (disambiguation) including Ο/ο