C2

{{Self-reference|For the Wikipedia C2 criterion for speedy deletion, see {{slink|Wikipedia:Criteria for speedy deletion#C2}}.}} {{Wiktionary}} '''C2''' or a derivative ('''C-2''', '''C²''', etc.) may refer to: {{TOC right}}

==Mathematics and physics== * ''C''₂, one of the common notations for the cyclic group of order 2 * ''C''² differentiability class * ''C''² or <math>\Complex^2</math>, the complex coordinate plane * ''c''² the square of the speed of light (in the mass–energy equivalence formula) * C2 (space group), three-dimensional space group number 5

==Biology== * C2 domain, a protein structural domain * C2 regulatory sequence for the insulin gene * Apolipoprotein C2, a human apolipoprotein * In human anatomy, C2 may refer to: ** Cervical vertebra 2, the axis, one of the cervical vertebrae of the vertebral column ** Cervical spinal nerve 2 * Chlorophyll c2, a form of chlorophyll * Complement component 2 * Procyanidin C2, a plant phenolic compound * Prodelphinidin C2, a plant phenolic compound * Vitamin C2 * the ATC code for ''Antihypertensives'', a subgroup of the Anatomical Therapeutic Chemical Classification System *C₂ fragments, one of the types of products of catabolism pathways * Haplogroup C-M217, also known as C2, a Human Y-chromosome DNA haplogroup

==Chemistry== * C₂, Diatomic carbon, a molecule made of two carbon atoms * C2=, ethylene, a two carbon alkene

==Codes or abbreviations== '''C2''' may be a code or abbreviation for: * C² Aquarii, a star * C² Centauri, a star * C2 (Code Geass), an anime character * C2 explosive, a form of plastic explosive * C2 pylon, a type of high voltage pylon * C2 radio class, a class in FM broadcasting in America * C2 (classification), a para-cycling classification * Group C2, the secondary class of Group C sports car racing * Nimrod NRA/C2, a 1982 Group C racing car * C2, an international standard paper size defined in ISO 216 (458×648&nbsp;mm) * C2, a level in the Common European Framework of Reference for Languages * C2, the NRS social grade between C1 and D * C2s, substances listed in Schedule II of the Controlled Substances Act in the United States * Command and control, the exercise of authority by a commanding officer over military forces in the accomplishment of a mission * Air Luxor IATA airline code * C2 Pictures, a film company related to Carolco Pictures * Bill C-2, various legislation of the Parliament of Canada * C2, or C₂ a note-octave in music, aka Low C

==Computing==

* C2, a computer security class, defined in the Trusted Computer System Evaluation Criteria * C2, a bytecode compiler that is part of the HotSpot virtual machine implementation * C2 (protocol), a 1985 Commodore file transfer protocol * C2 error, a read error of a compact disc * C2.com or WikiWikiWeb, the first user-editable website * C2 (consulting firm), an initialism for, and {{Abbr|aka|also known as}} Cunningham and Cunningham, a technology consulting firm founded by Ward Cunningham * Cryptomeria cipher, a cipher used in digital rights management * Command and control (malware) * Codec 2, speech compression codec.

==Transportation and space== * C2 class Melbourne tram * Bavarian C II (Ostbahn), an 1862 German steam locomotive * Bavarian C II.1, an 1857 German steam locomotive * Bavarian C II.2, an 1861 German steam locomotive * Chevrolet Corvette (C2), the generation of the Chevrolet Corvette produced between 1962 and 1967 * Citroën C2, a car produced by Citroën in 2004 * Cluster II (spacecraft), an ESA space mission * Ford C2 platform, an automobile platform produced by Ford since 2018 * GNR Class C2, a British 4-4-2 steam locomotive class * LNER Class C2, classified C1 during GNR ownership * Kawasaki C2, a bike * London Buses route C2 * LB&SCR C2 class, an 1893 British 0-6-0 steam locomotive * Circumferential Road 2 or C-2, an arterial road of Manila, Philippines * Saf-T-Liner C2, a school bus built by Thomas Built Buses * Saturn C-2, a 1960 conceptual American launch vehicle * Type C2 ship, a type of all-purpose cargo ship * C2 (yacht), a luxury motor yacht * Central Circular Route (Shuto Expressway) in Tokyo, Japan * Mei-Nikan Expressway, route C2 in Nagoya, Japan

==Military and aviation== * Command and control, the exercise of authority and direction by a commanding officer * C-2 (poison), developed in the ''Poison laboratory of the Soviet secret services'' * C2A1, Squad Automatic Weapon variant of the FN FAL formerly in Canadian Service * ACAZ C.2, a Belgian prototype fighter aircraft of the 1920s * AEG C.II, a German World War II armed reconnaissance aircraft * Aeronca C-2, an American airplane * AGO C.II, a German reconnaissance biplane of World War I * Cierva C.2, a 1921 Spanish experimental autogyro * DFW C.II, a World War I German reconnaissance aircraft * Fokker C-2, the American military version of the Fokker F.VII aircraft * C-2 Greyhound, the Grumman cargo aircraft of the United States Navy * {{HMS|C2}}, a British C class submarine of the Royal Navy * Kawasaki C-2, a military transport aircraft * LFG Roland C.II, a 1915 advanced German reconnaissance aircraft * LVG C.II, a 1910s German two-seat reconnaissance biplane * {{USS|C-2|SS-13}}, a C-class submarine of the United States Navy * {{USS|Charleston|C-2}}, a protected cruiser of the United States Navy

==Other== * C2, UEFA Cup Winners' Cup in football, later merged with UEFA Cup (now UEFA Europa League) * C2 Pictures, a film studio * C-2 visa, a nonimmigrant visa which allows individuals to travel to and from the headquarters of the United Nations * Coca-Cola C2, a soft drink launched by The Coca-Cola Company in 2004 * ''Conduit 2'', a 2011 first-person shooter video game * AEW Continental Classic, a professional wrestling tournament

==See also== * CO2 * CII (disambiguation) * 2C (disambiguation)

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