O2, O-2, o2, O2, O, O or O may refer to:
Science and technology
For vehicles, see § Vehicles.- O2 or dioxygen, the common allotrope of the chemical element oxygen
- O, the ion oxide
- O−2, the ion superoxide
- O+2, the ion dioxygenyl
- O, doubly ionized oxygen
- 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
- UOC O2, institutional repository of the Open University of Catalonia
- O2, the earliest defined spectral class for stars
Places
- 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), an indoor arena in Berlin, Germany
- O2 World (Hamburg), 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
- O2 (FireHouse album) (2000) album of the rock band FireHouse
- O2 (O-Town album) (2002) album by American boy band O-Town
- O2 (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
Businesses and organisations
- O2, trading name for Telefónica Europe, a European telecommunications provider
- O2 Store, a chain of retail stores owned and operated by Telefónica Europe, with regional subsidiaries:
- O2 (brand), Telefónica mobile network global brand name
- O2 (Ireland), merged into Three Ireland
- O2 (UK)
- O2 Czech Republic
- Telefónica Germany
- Telefónica 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 socially political TV channel
Vehicles and vessels
- 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
- Orbital O2, a tidal power turbine in Orkney
- GNR Class O2, a class of British steam locomotives classified O2 by both the GNR and the LNER
Other uses
- O-2, a pay grade in the US uniformed services
- 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
Topics referred to by the same termThis disambiguation page lists articles associated with the same title formed as a letter–number combination.If an internal link led you here, you may wish to change the link to point directly to the intended article. Category: