O2, O-2, o2, or similar orthography may refer to:

Science and technology

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  • Dioxygen (), the common allotrope of oxygen
  • Oxide (), an ion
  • Superoxide (), an ion
  • Dioxygenyl (), an ion
  • Doubly ionized oxygen (), an ion
  • O(2), the 2-dimensional orthogonal group in group theory
  • O2, an EEG electrode site according to the 10–20 system
  • SGI O2, a Unix workstation computer
  • O2, a class of O-type star
  • Orbital O2, a tidal power turbine in Orkney, Scotland
  • -O2, a compiler optimization tag

Places

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  • The O2, an entertainment district in London, England
  • The O2 Arena, the arena within The O2
  • O2 Arena (Prague) or Sazka Arena, an arena in Prague, Czech Republic
  • O2 Centre, an indoor shopping and entertainment centre on Finchley Road, London, England
  • O2 Residence, a part of the Jumeirah Lake Towers in Dubai, United Arab Emirates
  • O2 World (Berlin), former branding for Uber Arena, an indoor arena in Berlin, Germany
  • O2 World (Hamburg), former branding for Barclays Arena, an indoor arena in Hamburg, Germany
  • Otoyol 2, a motorway in Turkey called "O2"
  • The O2 (Dublin), the former name of 3Arena
  • Ring 2 (Aarhus), a road in Aarhus, Denmark, which appears as "O2" on signs
  • Ring 2 (Copenhagen), a road in Copenhagen, Denmark, which appears as "O2" on signs

Arts, entertainment and media

Film

  • Oxygen (2021 film) or O2, an American-French survival thriller film in production
  • O2 (2020 film), an Estonian-Latvia-Lithuanian-Finnish historical spy thriller film
  • O2 (2022 film), an Indian Tamil language survival thriller film
  • O2 (2024 film), an Indian Kannada language medical thriller film

Music

Albums

  • O<sub>2</sub> (FireHouse album) (2000) album of the rock band FireHouse
  • O2 (O-Town album) (2002) album by American boy band O-Town
  • O<sub>2</sub> (Tonéx album) (2002) album by Gospel singer Tonéx
  • O2: Avalon Remixed, a 2002 album by Avalon
  • O2 (Son of Dave album), 2006 album by Son of Dave

Songs

  • "O2", a song by Orange Range from Panic Fancy
  • "O2", a 2002 song by Sleater-Kinney from One Beat
  • "O2", a song by Suho from Self-Portrait

Other arts, entertainment and media

  • Ö2, a radio service for Austria and South Tyrol
  • O2, a character in Kirby 64: The Crystal Shards
  • UOC O2, institutional repository of the Open University of Catalonia

Businesses and organisations

  • O2 (brand), a global brand name owned by the Spanish telecommunications company Telefónica
  • O2 Store, a chain of retail stores owned and operated by Telefónica Europe, with regional subsidiaries:
  • O2 (Ireland), merged into Three Ireland
  • O2 (UK), a joint venture with Liberty Global
  • O2 Czech Republic
  • Telefónica Germany
  • O2 Slovakia
  • O2 Academy, a chain of music venues
  • O2 Wireless USA or H2O Wireless, a prepaid wireless service by Locus Telecommunications
  • O2TV, a Russian independent TV channel

Vehicles and military

  • Cessna O-2 Skymaster, a military twin-engine light aircraft
  • Douglas O-2, a military single-engine observation biplane
  • O 2-class submarine, a class of submarines of the Royal Netherlands Navy
  • Oldershaw O-2, a glider
  • SP&S Class O-2, a 1910 steam locomotives class
  • USS O-2 (SS-63), a 1918 United States O class submarine
  • GNR Class O2, a class of British steam locomotives classified O2 by both the GNR and the LNER

Pay grade

  • O-2, a uniformed services pay grade of the United States:
  • First lieutenant (United States) in the Army, Marine Corps, Air Force, and Space Force
  • Lieutenant (junior grade) in the Navy, Coast Guard, Public Health Service Commissioned Corps, and NOAA Commissioned Officer Corps

See also

  • 02 (disambiguation)
  • Oz (disambiguation)
  • 2O (disambiguation)
  • 2Q (disambiguation)
  • Q2 (disambiguation)