A CD or

compact disc The compact disc (CD) is a Digital media, digital optical disc data storage format co-developed by Philips and Sony to store and play digital audio recordings. It employs the Compact Disc Digital Audio (CD-DA) standard and was capable of hol ...

is a thin plastic silvery disc for audio recordings. CD or cd may also refer to:

Science and technology

Astronomy and cosmology

Cordoba Durchmusterung In astronomy, Durchmusterung or Bonner Durchmusterung (BD) is an astrometric star catalogue of the whole sky, published by the Bonn Observatory in Germany from 1859 to 1863, with an extension published in Bonn in 1886. The name comes from ('run-t ...

, a star catalog of the southern sky *

Cosmological decade ''The Five Ages of the Universe'' is a popular science book written by astrophysicists Fred Adams and Gregory P. Laughlin about the future of an expanding universe first published in 1999. Book contents The book ''The Five Ages of the Univ ...

or CÐ, a unit of time *

Type-cD galaxy The type-cD galaxy (also cD-type galaxy, cD galaxy) is a galaxy morphology classification, a subtype of type-D galaxy, type-D Elliptical galaxy#Sizes and shapes, giant elliptical galaxy. Characterized by a large galactic halo, halo of stars, the ...

, a galaxy morphology classification

Biology, ecology, and medicine

Coeliac disease Coeliac disease (British English) or celiac disease (American English) is a long-term autoimmune disorder, primarily affecting the small intestine. Patients develop intolerance to gluten, which is present in foods such as wheat, rye, spelt ...

, long term autoimmune disorder causing intolerance to gluten *

Conduct disorder Conduct disorder (CD) is a mental disorder diagnosed in childhood or adolescence that presents itself through a repetitive and persistent pattern of behavior that includes theft, lies, physical violence that may lead to destruction, and reck ...

, a psychological disorder *

Conservation Dependent A conservation-dependent species is a species which has been categorized as "Conservation Dependent" ("LR/cd") by the International Union for Conservation of Nature (IUCN), as dependent on conservation efforts to prevent it from becoming endang ...

or LR/cd, an IUCN category *

Cluster of differentiation The cluster of differentiation (also known as cluster of designation or classification determinant and often abbreviated as CD) is a protocol used for the identification and investigation of cell surface molecules providing targets for immunophe ...

, a protocol used for the identification of cell surface molecules on white blood cells *

Crohn's disease Crohn's disease is a type of inflammatory bowel disease (IBD) that may affect any segment of the gastrointestinal tract. Symptoms often include abdominal pain, diarrhea, fever, abdominal distension, and weight loss. Complications outside of the ...

Chlordane Chlordane, or chlordan, is an organochlorine compound that was used as a pesticide. It is a white solid. In the United States, chlordane was used for termite-treatment of approximately 30 million homes until it was banned in 1988. Chlordane was b ...

Communicable disease An infection is the invasion of tissue (biology), tissues by pathogens, their multiplication, and the reaction of host (biology), host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmis ...

Computing

CD-ROM A CD-ROM (, compact disc read-only memory) is a type of read-only memory consisting of a pre-pressed optical compact disc that contains computer data storage, data computers can read, but not write or erase. Some CDs, called enhanced CDs, hold b ...

, compact disc technology applied for use in computer data *

cd (command) is a shell command that changes the working directory. It is available in many shells and other applications that maintain a working directory. In some contexts, the command can perform actions other than change directory. Some environments p ...

, a shell command to change the current working directory *

continuous delivery Continuous delivery (CD) is a software engineering approach in which teams produce software in short cycles, ensuring that the software can be reliably released at any time. It aims at building, testing, and releasing software with greater speed ...

, a software development design practice *

continuous deployment Continuous deployment (CD) is a software engineering approach in which software functionalities are delivered frequently and through automated deployments. Continuous deployment contrasts with ''continuous delivery'' (also abbreviated CD), a sim ...

, a software development design practice * collision detection, CSMA/CD

Mathematics

* cd (elliptic function), one of Jacobi's elliptic functions

Other uses in science and technology

Cadmium Cadmium is a chemical element; it has chemical symbol, symbol Cd and atomic number 48. This soft, silvery-white metal is chemically similar to the two other stable metals in group 12 element, group 12, zinc and mercury (element), mercury. Like z ...

, symbol Cd, a chemical element *

Candela The candela (symbol: cd) is the unit of luminous intensity in the International System of Units (SI). It measures luminous power per unit solid angle emitted by a light source in a particular direction. Luminous intensity is analogous to radi ...

or cd, a unit of light intensity * -CD, the North American call sign suffix for Class A low-power television stations operating with digital signals *

Circular dichroism Circular dichroism (CD) is dichroism involving circular polarization, circularly polarized light, i.e., the differential Absorption (electromagnetic radiation), absorption of left- and right-handed light. Left-hand circular (LHC) and right-hand ci ...

, a form of spectroscopy *

Critical Dimension In the renormalization group analysis of phase transitions in physics, a critical dimension is the dimensionality of space at which the character of the phase transition changes. Below the lower critical dimension there is no phase transition. ...

, the minimum feature size that a projection system can print in photolithography * Drag coefficient or ''c_d'', a dimensionless quantity used to quantify the drag of an object in a fluid *

Cluster decay Cluster decay, also named heavy particle radioactivity, heavy ion radioactivity or heavy cluster decay," is a rare type of nuclear decay in which an atomic nucleus emits a small "cluster" of neutrons and protons, more than in an alpha particle, ...

, a rare mode of nuclear decay

Businesses and organizations

Government, military, and political

Canadian Forces' Decoration The Canadian Forces' Decoration (post-nominal letters "CD") is a Canadian award bestowed upon members of the Canadian Armed Forces who have completed twelve years of military service, with certain conditions. By convention, it is also given to t ...

, by post-nominal letters *

Centre Democrats (Denmark) The Centre Democrats (, CD) were a Danish political party. History The party was formed in 1973 by Erhard Jakobsen, a former MP and mayor of Gladsaxe, as a centrist splinter group from the Danish Social Democrats. It participated in both c ...

, a Danish former political party *

Centre Democrats (Netherlands) The Centre Democrats (, CD) was a List of political parties in the Netherlands, political party in the Netherlands. Founded in 1984 by members who split out from the Centre Party (Netherlands), Centre Party (CP), the Centre Democrats was joined ...

, a former political party of the Netherlands * ''

Centro Democratico Democratic Centre (, CD) is a centrism, centrist, Christian leftist and Social liberalism, social-liberal political party in Italy. Most of its members, including its leader Bruno Tabacci, are former Christian Democracy (Italy), Christian Democ ...

'', a political party in Italy *

Christian democracy Christian democracy is an ideology inspired by Christian social teaching to respond to the challenges of contemporary society and politics. Christian democracy has drawn mainly from Catholic social teaching and neo-scholasticism, as well ...

, a political ideology *

Civil defense Civil defense or civil protection is an effort to protect the citizens of a state (generally non-combatants) from human-made and natural disasters. It uses the principles of emergency management: Risk management, prevention, mitigation, prepara ...

, an effort to protect the citizens of a state from military attack and natural disasters *

Community of Democracies The Community of Democracies (C.O.D), established in 2000, is an intergovernmental coalition of states. Its aim is to bring together governments, civil society and the private sector in the pursuit of the common goal of supporting democratic rul ...

, an intergovernmental organization of democracies and democratizing countries *

Conference on Disarmament The Conference on Disarmament (CD) is a multilateral disarmament forum established by the international community to negotiate arms control and disarmament agreements based at the Palais des Nations in Geneva. The Conference meets annually in ...

, an international forum that negotiates multilateral arms control and disarmament agreements * '' Corps Diplomatique'', the collective body of foreign diplomats accredited to a particular country or body *

FBI Counterintelligence Division The Counterintelligence Division (CD) is a division of the FBI National Security Branch, National Security Branch of the Federal Bureau of Investigation. The division protects the United States against foreign intelligence, foreign intelligence ...

, the United States Federal Bureau of Investigation's division responsible for investigating espionage

Other business and organizations

Certificate of deposit A certificate of deposit (CD) is a time deposit sold by banks, thrift institutions, and credit unions in the United States. CDs typically differ from savings accounts because the CD has a specific, fixed term before money can be withdrawn wit ...

, a bank account in the United States with a fixed maturity date *

České dráhy České dráhy (English: ''Czech Railways''), often shortened to ČD, is the major Rail transport, railway operator in the Czech Republic providing regional and long-distance services. The company was established in January 1993, shortly after ...

or ČD, a railway operator of the Czech Republic * Commander of the Order of Distinction, a rank in the Jamaican Orders of Societies of Honour

Places

Central District, Seattle The Central Area (commonly called the Central District or The CDMary T. HenrySeattle Neighborhoods: Central Area -- Thumbnail History HistoryLink, March 10, 2001. Accessed online 2009-10-19.) is a mostly residential neighborhood in Seattle loca ...

, a district in Seattle *

Democratic Republic of the Congo The Democratic Republic of the Congo (DRC), also known as the DR Congo, Congo-Kinshasa, or simply the Congo (the last ambiguously also referring to the neighbouring Republic of the Congo), is a country in Central Africa. By land area, it is t ...

, by ISO 3166-1 alpha-2 country code ** .cd, the Internet domain of the Democratic Republic of the Congo * cd., abbreviation for caddesi, street, in Turkish

Other uses

* 400 (number), written CD in Roman numerals * 205 (number), written CD in hexadecimal * AD 400 (CD), a year of the Common Era *

C.D (Criminal or Devil) ''C.D (Criminal or Devil)'' is a 2024 Indian Telugu-language psychological thriller film directed by Krishna Annam and produced by Giridhar. It stars Adah Sharma, Viswant Duddumpudi, Mahesh Vitta, and Bharani Shankar as lead actors. Cast ...

, a psychological thriller movie * "CD", a song by

T2 (band) T2 were an English progressive rock band, best known for their 1970 album, '' It'll All Work Out in Boomland''. Origins T2 evolved from an earlier band, Neon Pearl, which was led by their drummer, Pete Dunton. Dunton was by 1968 a member of Pl ...

* cd, for

cord (unit) The cord is a unit of measure of dry volume used to measure firewood and pulpwood in the United States and Canada. A cord is the amount of wood that, when "racked and well stowed" (arranged so pieces are aligned, parallel, touching, and compact ...

of volume of wood * Geely CD, a coupe automobile made by Geely Automobile * Cairo Damascus or Damascus Document, a text found among the Dead Sea Scrolls * Committee Draft, a status in the

International Organization for Standardization The International Organization for Standardization (ISO ; ; ) is an independent, non-governmental, international standard development organization composed of representatives from the national standards organizations of member countries. M ...

* Companion dog (title), a title offered to dogs by the American Kennel Club for dog obedience *

Cross-dressing Cross-dressing is the act of wearing clothes traditionally or stereotypically associated with a different gender. From as early as pre-modern history, cross-dressing has been practiced in order to disguise, comfort, entertain, and express onesel ...

, the act of wearing clothing associated with the opposite sex * Corendon Dutch Airlines (IATA code) *

Sega CD The Sega CD, known as in most regions outside North America and Brazil, is a CD-ROM accessory and format for the Sega Genesis produced by Sega as part of the fourth generation of video game consoles. Originally released in November 1991, it ca ...

, also known as the Sega Mega-CD, a CD-ROM accessory and format for the Sega Genesis produced by Sega as part of the fourth generation of video game consoles **

Sonic CD is a 1993 platform game developed and published by Sega for the Sega CD. As Sonic the Hedgehog, the player attempts to protect an extraterrestrial body, Little Planet, from Doctor Robotnik. Like other '' Sonic'' games, Sonic runs through the ...

, a 1993 platform game developed and published by Sega for the Sega CD *

Bitter CD Erich Bitter Automobil GmbH (Bitter) is a premium sports-luxury automobile marque produced in Germany and later Austria. Founder Erich Bitter (1933–2023), a then retired racing driver turned automobile Car tuning, tuner, importer and ultimate ...

, a luxury hatchback coupé *

Cúcuta Deportivo Cúcuta Deportivo Fútbol Club S. A. (Spanish ), commonly referred to as Cúcuta Deportivo, is a professional Colombian football club from the city of Cúcuta. Founded on 10 September 1924, it is one of the oldest active football clubs in the co ...

, a Colombian football club