C is the third letter in the Latin alphabet. C or c may also refer to:

Computing

C (programming language) C (''pronounced'' '' – like the letter c'') is a general-purpose programming language. It was created in the 1970s by Dennis Ritchie and remains very widely used and influential. By design, C's features cleanly reflect the capabilities of ...

, developed at Bell Labs in 1972 * C, a

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 ...

digit * C, a

computable function Computable functions are the basic objects of study in computability theory. Informally, a function is ''computable'' if there is an algorithm that computes the value of the function for every value of its argument. Because of the lack of a precis ...

, the set of all computable decision problems * C:, or "Drive C", the default drive letter assignment for the default hard drive in DOS and Windows

Measurement

* °C,

Celsius The degree Celsius is the unit of temperature on the Celsius temperature scale "Celsius temperature scale, also called centigrade temperature scale, scale based on 0 ° for the melting point of water and 100 ° for the boiling point ...

temperature scale *

Carat (purity) The fineness of a precious metal object (coin, bar, jewelry, etc.) represents the weight of ''fine metal'' therein, in proportion to the total weight which includes alloying base metals and any impurities. Alloy metals are added to increase hard ...

* centi-, an SI prefix *

Coulomb The coulomb (symbol: C) is the unit of electric charge in the International System of Units (SI). It is defined to be equal to the electric charge delivered by a 1 ampere current in 1 second, with the elementary charge ''e'' as a defining c ...

, the SI derived unit for electric charge *

Cup (unit) The 'cup'' is a cooking weights and measures, cooking measure of volume, commonly associated with cooking and serving sizes. In the US customary system, it is equal to . Because actual drinking cups may differ greatly from the size of this unit, ...

, a unit of volume

Science

Troponin C Troponin C is a protein which is part of the troponin complex. It contains four calcium-binding EF hands, although different isoforms may have fewer than four functional calcium-binding subdomains. It is a component of thin filaments, along ...

, one of the three troponins *

Carbon Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...

, symbol C, a chemical element * Atomic carbon or C * ATC code C or cardiovascular system, a section of the Anatomical Therapeutic Chemical Classification System * Haplogroup C (mtDNA), a human mitochondrial DNA (mtDNA) haplogroup *

Haplogroup C-M130 (Y-DNA) Haplogroup C is a major Y-chromosome haplogroup, defined by UEPs M130/RPS4Y711, P184, P255, and P260, which are all SNP mutations. It is one of two primary branches of Haplogroup CF alongside Haplogroup F. Haplogroup C is found in ancient po ...

, a Y-chromosomal DNA (Y-DNA) haplogroup once called simply C *

Cytosine Cytosine () (symbol C or Cyt) is one of the four nucleotide bases found in DNA and RNA, along with adenine, guanine, and thymine ( uracil in RNA). It is a pyrimidine derivative, with a heterocyclic aromatic ring and two substituents attac ...

, nucleic acid * C (or Cys), an abbreviation for the amino acid

cysteine Cysteine (; symbol Cys or C) is a semiessential proteinogenic amino acid with the chemical formula, formula . The thiol side chain in cysteine enables the formation of Disulfide, disulfide bonds, and often participates in enzymatic reactions as ...

* C, a prefix for astronomical objects listed in the Caldwell catalogue, ranging from C1 to C109 * C, a prefix for astronomical star clusters, which follow the IAU's "Chhmm±ddd" format * ''c'', 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 vacuum * ''c'', the

speed of sound The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elasticity (solid mechanics), elastic medium. More simply, the speed of sound is how fast vibrations travel. At , the speed of sound in a ...

* ''c'', the

specific heat capacity In thermodynamics, the specific heat capacity (symbol ) of a substance is the amount of heat that must be added to one unit of mass of the substance in order to cause an increase of one unit in temperature. It is also referred to as massic heat ...

of a substance * ''c'', any constant * ''C'',

capacitance Capacitance is the ability of an object to store electric charge. It is measured by the change in charge in response to a difference in electric potential, expressed as the ratio of those quantities. Commonly recognized are two closely related ...

* C, symbol of

coulomb The coulomb (symbol: C) is the unit of electric charge in the International System of Units (SI). It is defined to be equal to the electric charge delivered by a 1 ampere current in 1 second, with the elementary charge ''e'' as a defining c ...

Charm quark The charm quark, charmed quark, or c quark is an elementary particle found in composite subatomic particles called hadrons such as the J/psi meson and the charmed baryons created in particle accelerator collisions. Several bosons, including th ...

() * C-value, DNA contained within a haploid nucleus

Technology

C battery The C battery (C size battery or R14 battery) is a standard size of dry cell battery typically used in medium-drain applications such as toys, flashlights, and musical instruments. As of 2007, C batteries accounted for 4% of alkaline primar ...

, a size of battery *

Capacitor In electrical engineering, a capacitor is a device that stores electrical energy by accumulating electric charges on two closely spaced surfaces that are insulated from each other. The capacitor was originally known as the condenser, a term st ...

or C * C battery, a type of battery for vacuum tube radios * C or C-rate, a rate of charge and discharge of a battery * C-states, the CPU power states

Mathematics

* C, a digit meaning twelve in

and other positional numeral systems with a radix of 13 or greater * ''C'', the

constant of integration In calculus, the constant of integration, often denoted by C (or c), is a constant term added to an antiderivative of a function f(x) to indicate that the indefinite integral of f(x) (i.e., the set of all antiderivatives of f(x)), on a connecte ...

* C, in

Roman numerals Roman numerals are a numeral system that originated in ancient Rome and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages. Numbers are written with combinations of letters from the Latin alphabet, eac ...

, the symbol for 100 * C or

\mathbb

, the set of all

complex number In mathematics, a complex number is an element of a number system that extends the real numbers with a specific element denoted , called the imaginary unit and satisfying the equation i^= -1; every complex number can be expressed in the for ...

s * ℭ or

\mathfrak c

, the

cardinality of the continuum In set theory, the cardinality of the continuum is the cardinality or "size" of the set of real numbers \mathbb R, sometimes called the continuum. It is an infinite cardinal number and is denoted by \bold\mathfrak c (lowercase Fraktur "c") or \ ...

* ''C'', the set of

continuous function In mathematics, a continuous function is a function such that a small variation of the argument induces a small variation of the value of the function. This implies there are no abrupt changes in value, known as '' discontinuities''. More preci ...

s * The

combination In mathematics, a combination is a selection of items from a set that has distinct members, such that the order of selection does not matter (unlike permutations). For example, given three fruits, say an apple, an orange and a pear, there are ...

or "choose" function * ''c'' space, the space of all convergent sequences in functional analysis * ⊂, notation indicating that a set is a

subset In mathematics, a Set (mathematics), set ''A'' is a subset of a set ''B'' if all Element (mathematics), elements of ''A'' are also elements of ''B''; ''B'' is then a superset of ''A''. It is possible for ''A'' and ''B'' to be equal; if they a ...

of another set

Music

* C (musical note), and keys based on it: **

C major C major is a major scale based on C, consisting of the pitches C, D, E, F, G, A, and B. C major is one of the most common keys used in music. Its key signature has no flats or sharps. Its relative minor is A minor and its parallel min ...

C minor C minor is a minor scale based on C, consisting of the pitches C, D, E, F, G, A, and B. Its key signature consists of three flats. Its relative major is E major and its parallel major is C major. The C natural minor scale is: Cha ...

* '' C Album'', an album by Kinki Kids * C major chord, a chord in popular music * , symbol used to designate

common time A time signature (also known as meter signature, metre signature, and measure signature) is an indication in music notation that specifies how many note values of a particular type fit into each measure ( bar). The time signature indicates the ...

* , symbol used to designate alla breve * "C", a composition by Francis Poulenc, one of ''Deux Poèmes de Louis Aragon''

Literature

* ''C'' (novel), a novel by Tom McCarthy * ''C'', a 1924 novel by Maurice Baring * ''C Magazine'', a magazine published by Cardinal Courier Media * '' "C" Is for Corpse'', the third novel in Sue Grafton's "Alphabet mystery" series, published in 1986 * C-lehti ('C-magazine'), a defunct Finnish computer magazine

Transportation

* Mercedes-Benz C-class * NZR C class (1873) train * NZR C class (1930) train * C, or 0-6-0 classification, a type of locomotive with three powered axles *C, the unofficial designation used by the U.S. Navy classification for Protected Cruisers and Peace Cruisers before the 1920 reclassification. * C (Los Angeles Railway) * C (S-train) a service on the S-train network in Copenhagen * C (New York City Subway service) * C Line (Los Angeles Metro) * Line C of the Buenos Aires Subte * Tokyo Metro Chiyoda Line, a subway service operated by the Tokyo Metro, labeled Logo of Tokyo Metro Chiyoda Line

* Chūō Line, a subway service operated by the Osaka Metro, labeled Osaka Metro Chuo line symbol

* RER C, a line in the RER of Paris * The official West Japan Railway Company service symbol for: ** JRW kinki-C

Kusatsu Line. ** JRW san-C

Sakai Line.

Sport

Captain (ice hockey) In ice hockey, the captain is the player designated by a team as the only person authorized to speak with the game officials regarding rule interpretations when the captain is on the ice. At most levels of play each team must designate one captai ...

Catcher Catcher is a position in baseball and softball. When a batter takes their turn to hit, the catcher crouches behind home plate, in front of the (home) umpire, and receives the ball from the pitcher. In addition to this primary duty, the catc ...

, a position in baseball *

Center (basketball) The center (C), or the centre, also known as the five, the big or the pivot, is one of the five Basketball position, positions in a regulation basketball game. The center is almost always the tallest player on the team, and often has a great deal ...

Center (gridiron football) Center or centre (C) is a position in American football. The center is the innermost Lineman (American football), lineman of the offensive line on a football team's Offense (sports), offense who passes (or "Snap (gridiron football), snaps") the b ...

Other uses

* Prefix "c", to specify a column number as in-source-locator in old citations * С, a letter of the Cyrillic alphabet * ''C'' (anime), by Tatsunoko Production, Fuji TV * C (grade), a satisfactory grade in education * C (plastic toy), a plastic toy from former Czechoslovakia * Citigroup, Inc.'s stock ticker symbol *

Gaius Gaius, sometimes spelled Caius, was a common Latin praenomen; see Gaius (praenomen). People * Gaius (biblical figure) (1st century AD) *Gaius (jurist) (), Roman jurist * Gaius Acilius * Gaius Antonius * Gaius Antonius Hybrida * Gaius Asinius Gal ...

or C * Center Party (Sweden), a Swedish political party *

Mansfield Smith-Cumming Captain (Royal Navy), Captain Sir Mansfield George Smith-Cumming (1 April 1859 – 14 June 1923) was a British naval officer who served as the first Chief of the Secret Intelligence Service, chief of the Secret Intelligence Service (SIS). Orig ...

or C (1859–1923), Chief of the SIS, the UK Secret Intelligence Service, also known as MI6 ** His successors as Chief of the SIS have since been generally known by his alias, C * C, also known as Max Denbigh, a character played by Andrew Scott in the film '' Spectre'' * c (IPA) in the International Phonetic Alphabet (IPA), the voiceless palatal stop * Dominical letter C for a

common year starting on Friday A common year starting on Friday is any non-leap year (i.e. a year with 365 days) that begins on Friday, 1 January, and ends on Friday, 31 December. Its dominical letter hence is C. The most recent year of such kind was 2021, and the next one wil ...

* C, the production code for the 1964 ''Doctor Who'' serial '' The Edge of Destruction'' * Charlie, the military time zone code for UTC+03:00 * c, alternative name for

Grimes Claire Elise Boucher (; born March 17, 1988), known professionally as Grimes, is a Canadian musician, singer, songwriter, and record producer. Her lyrics often touch on science fiction and feminist themes. The visuals in her videos are elabora ...

* Farmall C, a tractor produced by International Harvester from 1948 to 1951 * C (restaurant), a restaurant in Tampere, Finland