O (disambiguation)

O is the fifteenth letter of the modern Latin alphabet.

O may also refer to:


  • 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
  • , a consonant in Hangul, the Korean alphabet
  • , a consonant in Burmese script
  • /o/, close-mid back rounded vowel in the International Phonetic Alphabet

Vo (letter)

Arts and entertainmentEdit

Film and televisionEdit

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


Media and publicationsEdit



  • 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"





  • 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


  •  , 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



  • O Brook, a short river in Devon, England


  • 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
  • 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


  • 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 usesEdit

See alsoEdit