C3, C-3, C.3, C03, C.III or C-III may refer to:

Life and biology

C3-convertase C3 convertase (''C4bC2b'', formerly ''C4b2a'') belongs to family of serine proteases and is necessary in innate immunity as a part of the complement system which eventuate in opsonisation of particles, release of inflammatory peptides, C5 con ...

, an enzyme *

Complement component 3 Complement may refer to: The arts * Complement (music), an interval that, when added to another, spans an octave ** Aggregate complementation, the separation of pitch-class collections into complementary sets * Complementary color, in the vi ...

, a protein of the innate immune system * Apolipoprotein C3, a human very low density lipoprotein * ATC code C03 ''Diuretics'', a subgroup of the Anatomical Therapeutic Chemical Classification System * Castavinol C3, a natural phenolic compound found in red wines * Cytochrome-c3 hydrogenase, an enzyme * Haplogroup C-M217, called C3 in older publications * In human anatomy, C3 may refer to: **

Cervical vertebra 3 In tetrapods, cervical vertebrae (: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In sauropsid s ...

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

Cervical spinal nerve 3 The cervical spinal nerve 3 (C3) is a spinal nerve of the cervical segment The spinal cord is a long, thin, tubular structure made up of nervous tissue that extends from the medulla oblongata in the lower brainstem to the lumbar region of the v ...

* Clinical Cell Culture, a medical technology company * C03, Malignant neoplasm of gum ICD-10 code * C3 Collaborating for Health, a health-promotion NGO * C3: an EEG electrode site according to the 10-20 system

Military

* C³, Command, control, and communications, a military concept * C-3 (plastic explosive), a plastic explosive related to C4 * C-3, a United States military designation for the

Ford Trimotor The Ford Trimotor (also called the "Tri-Motor", and nicknamed the "Tin Goose") is an American Trimotor, three-engined transport plane, transport aircraft. Production started in 1925 by the companies of Henry Ford and ended on June 7, 1933, afte ...

* the designation for several German World War I and World War II armed reconnaissance aircraft ** AEG C.III ** AGO C.III, a reconnaissance biplane of World War I ** Albatros C.III ** DFW C.III, a DFW aircraft * NAG C.III, an engine powering the Gotha G.IV aircraft * C-3, a U.S. military transport version of the Martin 4-0-4 * Type C3 submarine (disambiguation), a World War II Imperial Japanese Navy cargo carrier submarine * Spanish submarine ''C-3'' * HMS ''C3'', a 1906 British C class submarine *

Type C3-class ship Type C3-class ships were the third type of cargo ship designed by the United States Maritime Commission (MARCOM) in the late 1930s. As it had done with the Type C1 ships and Type C2 ships, MARCOM circulated preliminary plans for comment. The d ...

, a type of merchant cargo ships of United States Maritime Commission "C" design * USS ''C-3'' (SS-14), a 1909 United States C class submarine * USS ''Baltimore'' (C-3), an 1888 protected cruiser of the United States Navy * Garda Crime and Security Branch (CSB), domestic security agency of Ireland's national police, also known as "C3" * C3 Howitzer, a lengthened variant of the M101 used by the Canadian Armed Forces

Technology

* C₃,

characteristic energy A characteristic is a distinguishing feature of a person or thing. It may refer to: Computing * Characteristic (biased exponent), an ambiguous term formerly used by some authors to specify some type of exponent of a floating point number * Charac ...

, in astrodynamics, a measure of the rocket energy for an interplanetary mission that requires attaining an orbital velocity above escape velocity * C₃, the chemical symbol for ** Tricarbon ** Cyclopropatriene * C3.ai, an AI company founded by Thomas Siebel *

Delfi-C3 Delfi-C3 is a CubeSat satellite constructed by students at the Delft University of Technology in the Netherlands. It is a 3-unit CubeSat, and was launched at 03:53:42 on 28 April 2008, as part of the NLS-4 mission, aboard a PSLV rocket, from the ...

, a Dutch CubeSat satellite * Saturn C-3, a 1960 rocket in the Saturn C series *

Chaos Communication Congress The Chaos Communication Congress is an annual hacker conference organized by the Chaos Computer Club. The congress features a variety of lectures and workshops on technical and political issues related to security, cryptography, privacy and ...

, the biggest annual hacker event in Europe * Chrysler Comprehensive Compensation System, important in the development of Extreme Programming * VIA C3, a computer processor * ''

Creatures 3 ''Creatures 3'' is the third game in the ''Creatures (video game series), Creatures'' artificial life, a-life game series made by Guerrilla Cambridge, Creature Labs. In this installment, the Shee (Creatures), Shee have left Albia in a spaceship, t ...

'', a 1999 video game * '' Crysis 3'', a 2013 video game * Cluster 3, also known as Samba, an ESA satellite

Transportation

* Aeronca C-3, an American airplane * Bavarian C III, a German steam locomotive model * Bavarian C III (Ostbahn), an 1867 German steam locomotive model * Chevrolet Corvette (C3), the third production design of the Chevrolet Corvette * Circumferential Road 3 or C-3, an arterial road of Manila, Philippines * Cierva C.3, a 1921 Spanish experimental autogyro * Citroën C3, a car * Cowin C3, a car * LB&SCR C3 class, a British LB&SCR locomotive * London Buses route C3, a Transport for London contracted bus route * C3 (railcar), a bi-level railcar built by Kawasaki Railcar for the non-electrified branches of the Long Island Rail Road * Nimrod NRA/C3, a 1983 Group C racing car never achieved * Yamaha C3, a 2007 liquid cooled 49cc four-stroke motor scooter * Two different ring expressways in Japan that are numbered C3: ** Tokyo Gaikan Expressway in Tokyo, Saitama and Chiba Prefectures ** Tōkai-Kanjō Expressway in Aichi, Gifu and Mie Prefectures

Music

* Hammond C3 organ * High C in music (c3 in European notation) * Low C in music (C3 in American notation) * '' Tha Carter III'', the title of an album by rapper Lil Wayne * C3 Presents, independent American concert promoters

Other uses

* C3 (classification), a para-cycling classification * C-3 (TV channel), a children's channel on the QUBE cable system that later became Nickelodeon * ''C³'' (light novel), a 2011 Japanese light novel series and anime by Hazuki Minase * C3, a New Zealand logistics company owned by

Linx Cargo Care Group Linx Cargo Care Group is a transportation and logistics company in Australia and New Zealand, headquartered in Sydney. History LINX Cargo Care Group was founded in August 2016 when Asciano Limited, Asciano was broken up in August 2016. A group ...

* C3, the code for permission to use specific land or premises for dwellings in

town and country planning in the United Kingdom Town and country planning in the United Kingdom is the part of UK land law which concerns land use planning. Its goal is to ensure sustainable economic development and a better environment. Each country of the United Kingdom has its own planni ...

* C3, the

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 ...

in football * C3, a 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 ...

* Tippmann C-3, a pump-action paintball marker that uses propane gas * C3 Church Global, a worldwide Pentecostal denomination * C3, a class in FM radio broadcasting in North America * Argus C3, a 35mm rangefinder camera * Nokia C3 (disambiguation), various Nokia cellphones * Caldwell 3 ( NGC 4236), a barred spiral galaxy in Draco * C3 policing, a methodology being employed by police to combat gangs in Springfield, Massachusetts *

Nielsen ratings Nielsen Media Research (NMR) is an American firm that measures media audiences, including television, radio, theatre, films (via the AMC Theatres MAP program), and newspapers. Headquartered in New York City, it is best known for the Nielsen rat ...

that include recorded programs watched three days later * Championing Community Children, a Philippine charitable organization abbreviated as C3 * Charles Keating III (born 1955), American former swimmer and real estate executive *

Charles III Charles III (Charles Philip Arthur George; born 14 November 1948) is King of the United Kingdom and the 14 other Commonwealth realms. Charles was born at Buckingham Palace during the reign of his maternal grandfather, King George VI, and ...

(born 1948), King of the United Kingdom and 14 other Commonwealth realms since 2022. * C-III Capital Partners, an

asset management Asset management is a systematic approach to the governance and realization of all value for which a group or entity is responsible. It may apply both to tangible assets (physical objects such as complex process or manufacturing plants, infrastr ...

and commercial real estate services company *

Hexadecimal Hexadecimal (also known as base-16 or simply hex) is a Numeral system#Positional systems in detail, positional numeral system that represents numbers using a radix (base) of sixteen. Unlike the decimal system representing numbers using ten symbo ...