C2 or a derivative (C-2, C², etc.) may refer to:

Mathematics and physics

* ''C''₂, one of the common notations for the

cyclic group In group theory, a branch of abstract algebra in pure mathematics, a cyclic group or monogenous group is a group, denoted C''n'', that is generated by a single element. That is, it is a set of invertible elements with a single associative bi ...

of order 2 * ''C''²

differentiability class In mathematical analysis, the smoothness of a function is a property measured by the number of continuous derivatives it has over some domain, called ''differentiability class''. At the very minimum, a function could be considered smooth if ...

* ''c''² the square of the

speed of light The speed of light in vacuum, commonly denoted , is a universal physical constant that is important in many areas of physics. The speed of light is exactly equal to ). According to the special theory of relativity, is the upper limit fo ...

(in the mass–energy equivalence formula)

Biology

C2 domain A C2 domain is a protein structural domain involved in targeting proteins to cell membranes. The typical version (PKC-C2) has a beta-sandwich composed of 8 β-strands that co-ordinates two or three calcium ions, which bind in a cavity formed by ...

, a protein structural domain *

C2 regulatory sequence Transcription of insulin is regulated by the binding of various transcription factors to the ~400 base pairs before the insulin transcription start site, called the "insulin regulatory sequence". This sequence is made up of several distinct region ...

for the insulin gene *

Apolipoprotein C2 Apolipoprotein C-II (Apo-CII, or Apoc-II), or apolipoprotein C2 is a protein that in humans is encoded by the gene. The protein encoded by this gene is secreted in plasma where it is a component of very low density lipoproteins and chylomicron ...

, a human apolipoprotein * In human anatomy, C2 may refer to: **

Cervical vertebra 2 In anatomy, the axis (from Latin ''axis'', "axle") or epistropheus is the second cervical vertebra (C2) of the spine, immediately inferior to the atlas, upon which the head rests. The axis' defining feature is its strong odontoid process (bon ...

, the axis, one of the cervical vertebrae of the vertebral column **

Cervical spinal nerve 2 The cervical spinal nerve 2 (C2) is a spinal nerve of the cervical segment.American Medical Association

* Chlorophyll c2, a form of chlorophyll *

Complement component 2 Complement C2 is a protein that in humans is encoded by the ''C2'' gene. The protein encoded by this gene is part of the classical pathway of the complement system, acting as a multi-domain serine protease. Deficiency of C2 has been associated wit ...

Procyanidin C2 Procyanidin C2 is a B type proanthocyanidin trimer, a type of condensed tannin. Natural occurrences Procyanidin C2 is found in grape seeds (''Vitis vinifera'') and wine, in barley (''Hordeum vulgare''), malt and beer, in ''Betula spp.'', in ' ...

, a plant phenolic compound *

Prodelphinidin C2 Prodelphinidin C2 is a prodelphinidin trimer found in malt Malt is germinated cereal grain that has been dried in a process known as " malting". The grain is made to germinate by soaking in water and is then halted from germinating furthe ...

, a plant phenolic compound * Vitamin C2, a name sometimes used for Choline * the ATC code for ''

Antihypertensives Antihypertensives are a class of drugs that are used to treat hypertension (high blood pressure). Antihypertensive therapy seeks to prevent the complications of high blood pressure, such as stroke and myocardial infarction. Evidence suggests that ...

'', a subgroup of the Anatomical Therapeutic Chemical Classification System *C₂ fragments, one of the types of products of

catabolism Catabolism () is the set of metabolic pathways that breaks down molecules into smaller units that are either oxidized to release energy or used in other anabolic reactions. Catabolism breaks down large molecules (such as polysaccharides, lipids ...

pathways *

Haplogroup C-M217 } Haplogroup C-M217, also known as C2 (and previously as C3), is a Y-chromosome DNA haplogroup. It is the most frequently occurring branch of the wider Haplogroup C (M130). It is found mostly in Central Asia, Eastern Siberia and significant fre ...

, also known as C2, a

Human Y-chromosome DNA haplogroup In human genetics, a human Y-chromosome DNA haplogroup is a haplogroup defined by mutations in the non- recombining portions of DNA from the male-specific Y chromosome (called Y-DNA). Many people within a haplogroup share similar numbers o ...

Chemistry

* C₂,

Diatomic carbon Diatomic carbon (systematically named dicarbon and 1λ2,2λ2-ethene), is a green, gaseous inorganic chemical with the chemical formula C=C (also written 2or C2). It is kinetically unstable at ambient temperature and pressure, being removed throug ...

, a molecule made of two carbon atoms * C2=,

ethylene Ethylene ( IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds). 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) In paralympic sport, C2 is a para-cycling classification. The UCI recommends this be coded as MC2 or WC2. Definition PBS defined this classification as "Riders with upper or lower limb impairments and moderate to severe neurological ." ''The Te ...

, a para-cycling classification *

Group C2 Group C was a category of sports car racing introduced by the FIA in 1982 and continuing until 1993, with ''Group A'' for touring cars and ''Group B'' for GTs. It was designed to replace both Group 5 special production cars (closed top touri ...

, the secondary class of Group C sports car racing *

BRDC C2 Championship The BRDC C2 Championship (sometimes referred to as the British C2 Championship) was a short lived sports car racing series which ran from 1988 to 1990. The series was for Group C cars which fit into the smaller, less powerful, and cheaper C2 categor ...

, a short lived sports car racing series which ran from 1988 to 1990 *

Nimrod NRA/C2 The Nimrod NRA/C2 was the only Group C racing car ever built by Nimrod Racing Automobiles in partnership with Aston Martin. It ran initially in 1982 in the World Endurance Championship before also joining the IMSA GT Championship. The final NR ...

, a 1982 Group C racing car * C2, an international standard paper size defined in

ISO 216 ISO 216 is an international standard for paper sizes, used around the world except in North America and parts of Latin America. The standard defines the "A", "B" and "C" series of paper sizes, including A4, the most commonly available paper si ...

(458×648 mm) * C2, a level in the Common European Framework of Reference for Languages * C2, the

NRS social grade The NRS social grades are a system of demographic classification used in the United Kingdom. They were originally developed by the National Readership Survey (NRS) to classify readers, but are now used by many other organisations for wider appl ...

between C1 and D *

Command and control Command and control (abbr. C2) is a "set of organizational and technical attributes and processes ... hatemploys human, physical, and information resources to solve problems and accomplish missions" to achieve the goals of an organization or e ...

, 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 C or Do is the first note and semitone of the C major scale, the third note of the A minor scale (the relative minor of C major), and the fourth note (G, A, B, C) of the Guidonian hand, commonly pitched around 261.63 Hz. The actual frequen ...

Computing

* C2, a computer security class, defined in the

Trusted Computer System Evaluation Criteria Trusted Computer System Evaluation Criteria (TCSEC) is a United States Government Department of Defense (DoD) standard that sets basic requirements for assessing the effectiveness of computer security controls built into a computer system. The TCS ...

* C2, a bytecode compiler that is part of the

HotSpot Hotspot, Hot Spot or Hot spot may refer to: Places * Hot Spot, Kentucky, a community in the United States Arts, entertainment, and media Fictional entities * Hot Spot (comics), a name for the DC Comics character Isaiah Crockett * Hot Spot (Tra ...

virtual machine implementation *

C2 (protocol) Punter is a protocol for file transfer developed in the 1980s by Steve Punter. There are various types of Punter such as PET Transfer Protocol (''PTP''), ''C1'' and ''C2''. PET Transfer Protocol The PET Transfer Protocol (''PTP''), also known a ...

, a 1985 Commodore file transfer protocol * C2 error, a read error of a compact disc * C2.com or WikiWikiWeb, the first user-editable website * Cryptomeria cipher, a cipher used in digital rights management *

Command and control (malware) A botnet is a group of Internet-connected devices, each of which runs one or more bots. Botnets can be used to perform Distributed Denial-of-Service (DDoS) attacks, steal data, send spam, and allow the attacker to access the device and its co ...

* Codec 2, speech compression codec.

Transportation and space

* C2 class Melbourne tram *

Bavarian C II (Ostbahn) The Bavarian Class C, later C II, was a German steam locomotive with the Bavarian Eastern Railway (''Bayerische Ostbahn''). These engines were the first six-coupled vehicles in Bavaria with external frames. In addition they had Stephenson valv ...

, an 1862 German steam locomotive *

Bavarian C II.1 The Bavarian C II was a class of early German steam locomotives operated by the Royal Bavarian State Railways (''Königlich Bayerische Staatsbahn''). Articulated variant (''Stütztender'') The first C IIs were built experimentally as articulat ...

, an 1857 German steam locomotive *

Bavarian C II.2 The Bavarian C II was a class of early German steam locomotives operated by the Royal Bavarian State Railways (''Königlich Bayerische Staatsbahn''). Articulated variant (''Stütztender'') The first C IIs were built experimentally as articulat ...

, an 1861 German steam locomotive *

Chevrolet Corvette (C2) The Chevrolet Corvette (C2) is the second generation of the Chevrolet Corvette sports car, produced by the Chevrolet division of General Motors (GM) for the 1963 through 1967 model years. History Origin and development The 1963 Sting Ray pr ...

, the generation of the Chevrolet Corvette produced between 1962 and 1967 *

Citroën C2 The Citroën C2 is a supermini that was produced by the French manufacturer Citroën, with production starting August 2003. It replaced the Citroën Saxo and was built at the Aulnay plant, on the outskirts of Paris. The Citroën C2 was disconti ...

, a car produced by Citroën in 2004 *

Cluster II (spacecraft) Cluster II is a space mission of the European Space Agency, with NASA participation, to study the Earth's magnetosphere over the course of nearly two solar cycles. The mission is composed of four identical spacecraft flying in a tetrahedral f ...

, an ESA space mission *

GNR Class C2 The Great Northern Railway class C2 locomotives were a class of 4-4-2 tank locomotives built by the Great Northern Railway (GNR) between 1898 and 1907. They were used on local and commuter passenger trains in Yorkshire and North London. They ...

, a British 4-4-2 steam locomotive class * LNER Class C2, classified C1 during GNR ownership *

Kawasaki C2 The Kawasaki C2SS 120 and C2TR 120 Roadrunner were Kawasaki motorcycles made from 1964 to 1969. The C2SS was designed as a street scrambler; a road machine powered by a single cylinder, two stroke, rotary disc valve engine with a displacement ...

, a bike * London Buses route C2 *

LB&SCR C2 class The London, Brighton and South Coast Railway C2 class was a class of 0-6-0 steam locomotives, intended for heavy freight trains. Fifty-five were built by the Vulcan Foundry between 1893 and 1902 to the design of Robert J. Billinton. Forty-five ...

, 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 Type C2 ships were designed by the United States Maritime Commission (MARCOM) in 1937–38. They were all-purpose cargo ships with five holds, and U.S. shipyards built 328 of them from 1939 to 1945. Compared to ships built before 1939, the C2s w ...

, a type of all-purpose cargo ship * C2 (yacht), a luxury motor yacht *

Central Circular Route (Shuto Expressway) The , signed as Route C2, is one of the routes of the Shuto Expressway system serving the central part of the Greater Tokyo Area. The route is a circumferential highway running through the outer wards of Tokyo. The route is the middle of f ...

in Tokyo, Japan *

Mei-Nikan Expressway The , or , is a partially completed tolled expressway in Japan. It is owned and operated by the Central Nippon Expressway Company. Upon completion, the expressway will form a second ring road around Nagoya in conjunction with the Isewangan Expres ...

, route C2 in Nagoya, Japan

Military and aviation

* C2A1, Squad Automatic Weapon variant of the FN FAL formerly in Canadian Service *

C-2 Greyhound The Grumman C-2 Greyhound is a twin-engine, high-wing cargo aircraft designed to carry supplies, mail, and passengers to and from aircraft carriers of the United States Navy. Its primary mission is carrier onboard delivery (COD). The aircraft ...

, the Grumman cargo aircraft of the United States Navy *

ACAZ C.2 The ACAZ C.2, ''Ateliers de Construction Aeronautique de Zeebruge'', was a prototype Belgian biplane fighter aircraft built in the 1920s. Design and development Built entirely of Duralumin metal, it was an advanced design at the time of its fi ...

, a Belgian prototype fighter aircraft of the 1920s *

AEG C.II The AEG C.II was a German two-seat biplane reconnaissance aircraft produced in small numbers from October 1915. It was a slightly smaller version of the C.I with better performance, redesigned cockpit for both pilot and observer/bombardier, new r ...

, a German World War II armed reconnaissance aircraft * AGO C.II, a German reconnaissance biplane of World War I *

Cierva C.2 __NOTOC__ The Cierva C.2 was an experimental autogyro built by Juan de la Cierva Juan de la Cierva y Codorníu, 1st Count of la Cierva (; 21 September 1895 in Murcia, Spain – 9 December 1936 in Croydon, United Kingdom) was a Spanish civil ...

, a 1921 Spanish experimental autogyro *

DFW C.II __NOTOC__ The DFW C.I was a German reconnaissance aircraft produced during World War I. Derived from the company's B.I design of 1914, the C.I kept the same basic fuselage design, but dispensed with the B.I's distinctive crescent-shaped wings, r ...

, a World War I German reconnaissance aircraft * Fokker C-2, the American military version of the Fokker F.VII aircraft * , a British C class submarine of the Royal Navy *

Kawasaki C-2 The Kawasaki C-2 (previously XC-2 and C-X) is a mid-size, twin- turbofan engine, long range, high speed military transport aircraft developed and manufactured by Kawasaki Aerospace Company. In June 2016, the C-2 formally entered service with th ...

, a military transport aircraft * LFG Roland C.II, a 1915 advanced German reconnaissance aircraft * LVG C.II, a 1910s German two-seat reconnaissance biplane * , a C-class submarine of the United States Navy * , a protected cruiser of the United States Navy * A military term for

C-2 (poison) The poison laboratory of the Soviet secret services, alternatively known as Laboratory 1, Laboratory 12, and Kamera (which means "The Cell" in Russian language, Russian), was a covert Research and development , research-and-development facili ...

, developed in the ''Poison laboratory of the Soviet secret services''

Other

* C2,

UEFA Cup Winners' Cup The UEFA Cup Winners' Cup was a European football club competition contested annually by the winners of domestic cup competitions. The cup was, chronologically, the second seasonal inter-European club competition organised by UEFA. The tourn ...

in football, later merged with UEFA Cup (now

UEFA Europa League The UEFA Europa League (abbreviated as UEL, or sometimes, UEFA EL), formerly the UEFA Cup, is an annual football club competition organised since 1971 by the Union of European Football Associations (UEFA) for eligible European football clubs. ...

) * C2 Pictures, a film studio *

C-2 visa The C-2 visa is a non-immigrant visa which allows individuals to travel to United States for the purpose of immediate and continuous transit to or from the headquarters of the United Nations, or for United Nations officials transiting the US to a ...

, 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