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 abstract algebra, a cyclic group or monogenous group is a Group (mathematics), group, denoted C_n (also frequently \Z_n or Z_n, not to be confused with the commutative ring of P-adic number, -adic numbers), that is Generating set of a group, ge ...

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 (''differentiability class)'' it has over its domain. A function of class C^k is a function of smoothness at least ; t ...

* ''C''² or

\Complex^2

, the

complex coordinate plane In mathematics, the ''n''-dimensional complex coordinate space (or complex ''n''-space) is the set of all ordered ''n''-tuples of complex numbers, also known as ''complex vectors''. The space is denoted \Complex^n, and is the ''n''-fold Cartesia ...

* ''c''² the square of the

speed of light The speed of light in vacuum, commonly denoted , is a universal physical constant exactly equal to ). It is exact because, by international agreement, a metre is defined as the length of the path travelled by light in vacuum during a time i ...

(in the mass–energy equivalence formula)

Biology

* C2 domain, 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 regions ...

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 chylomicr ...

, 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 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 wi ...

Procyanidin C2 Procyanidin C2 is a B type proanthocyanidin trimer (chemistry), 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 ''Be ...

, a plant phenolic compound * Prodelphinidin C2, a plant phenolic compound * Vitamin C2 (disambiguation) * the ATC code for '' Antihypertensives'', 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, lipid ...

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 freq ...

, also known as C2, a

Human Y-chromosome DNA haplogroup In human genetics, a human Y-chromosome DNA haplogroup is a haplogroup defined by specific mutations in the non-Genetic recombination, recombining portions of DNA on the male-specific Y chromosome (Y-DNA). Individuals within a haplogroup share ...

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 bond, carbon–carbon doub ...

, 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 sports, 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 T ...

, a para-cycling classification * Group C2, the secondary class of Group C sports car racing * BRDC C2 Championship, a short lived sports car racing series which ran from 1988 to 1990 * Nimrod NRA/C2, 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, which includes the A4, the most commonly availabl ...

(458×648 mm) * C2, a level in the

Common European Framework of Reference for Languages The Common European Framework of Reference for Languages: Learning, Teaching, Assessment, abbreviated in English as CEFR, CEF, or CEFRL, is a guideline used to describe achievements of learners of foreign languages across Europe and, increasingl ...

* 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 have since been used by many other organisations for w ...

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 Air Luxor was an airline based in Luxor Plaza in Lisbon, Portugal, operating a limited number of scheduled flights out of Portela Airport, Lisbon. The airline's operations were located in Building C1 and Hangar 7 in Delta Park, an area in Lis ...

IATA airline code *

C2 Pictures C2 Pictures was an American Independent business, independent Media company, media-entertainment company that specialized in Film production, film and television production. History The company was established in 1998 by Carolco Pictures co-fou ...

, a film company related to Carolco Pictures *

Bill C-2 Bill C-2 refers to various legislation introduced into the House of Commons of Canada. Because Bill C-1 is a ''pro forma'' bill asserting the independence of Parliament, Bill C-2 is the first substantive bill introduced into each session of the Ho ...

, 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 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 frequency has depen ...

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 TC ...

* C2, a bytecode compiler that is part of the HotSpot virtual machine implementation * C2 (protocol), a 1985 Commodore file transfer protocol *

C2 error A C2 error is a read error of a Compact Disc. C2 errors can to a degree be recovered by the hardware error detection and correction scheme. A CD drive can have extraction errors when the data on the disc is not readable due to scratches or smudges. ...

, 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) * 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 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 Chevrolet Corvette#Second generation-C2 (1963–1967), second-generation Chevrolet Corvette, Corvette sports car, produced by the Chevrolet division of General Motors (GM) for the 1963 through 1967 model years. ...

, the generation of the Chevrolet Corvette produced between 1962 and 1967 * Citroën C2, a car produced by Citroën in 2004 *

Cluster II (spacecraft) Cluster II was 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 was composed of four identical spacecraft flying in a Tetrahedron, t ...

, an ESA space mission *

Ford C2 platform Ford commonly refers to: * Ford Motor Company, an automobile manufacturer founded by Henry Ford * Ford (crossing), a shallow crossing on a river Ford may also refer to: Ford Motor Company * Henry Ford, founder of the Ford Motor Company * Ford F ...

, 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 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 we ...

, 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 23 special wards, wards of Tokyo. The route is ...

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 The Aeronca C-2 is an American light monoplane designed by Jean A. Roche and built by Aeronca Aircraft. Development Roche Monoplane Jean A. Roche was a U.S. Army engineer at McCook Field airfield in Dayton, Ohio. Roche developed an aircraft ...

, 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 C-2 Greyhound is a twin-engine, high-wing cargo aircraft designed to carry supplies, mail, and passengers to and from List of United States Navy aircraft carriers, aircraft carriers of the United States Navy. Its primary mission is ...

, the Grumman cargo aircraft of the United States Navy * , 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 * , a C-class submarine of the United States Navy * , a protected cruiser of the United States Navy

Other

* C2,

UEFA Cup Winners' Cup The UEFA Cup Winners' Cup was a European association football, football club competition contested annually by the winners of domestic cup competitions. The competition's official name was originally the European Cup Winners' Cup; it was renam ...

in football, later merged with UEFA Cup (now

UEFA Europa League The UEFA Europa League (UEL), usually known simply as the Europa League, is an annual association football, football club competition organised since 1971 by the UEFA, Union of European Football Associations (UEFA) for eligible European footb ...

) *

, 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