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

Science and technology

Astronomy and cosmology

* Cordoba Durchmusterung, a star catalog of the southern sky * Cosmological decade or CÐ, a unit of time * Type-cD galaxy, a galaxy morphology classification

Biology, ecology, and medicine

* Coeliac disease, long term autoimmune disorder causing intolerance to gluten * Conduct disorder, a psychological disorder * Conservation Dependent or LR/cd, an IUCN category * Cluster of differentiation, a protocol used for the identification of cell surface molecules on white blood cells * Crohn's disease * Chlordane *Communicable disease

Computing

* CD-ROM, compact disc technology applied for use in computer data * cd (command), a command line command to change the current working directory in operating systems * continuous delivery, a software development design practice * continuous deployment, 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, symbol Cd, a chemical element * Candela 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, a form of spectroscopy * Photolithography#Resolution in projection systems, Critical Dimension, 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, a rare mode of nuclear decay

Businesses and organizations

Government, military, and political

* Canadian Forces Decoration, by post-nominal letters * Centre Democrats (Denmark), a Danish former political party * Centre Democrats (Netherlands), a former political party of the Netherlands * ''Centro Democratico'', a political party in Italy * Christian democracy, a political ideology * Civil defense, an effort to protect the citizens of a state from military attack and natural disasters * Community of Democracies, an intergovernmental organization of democracies and democratizing countries * Conference on Disarmament, 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 United States Federal Bureau of Investigation's division responsible for investigating espionage

Other business and organizations

* Certificate of deposit, a bank account in the United States with a fixed maturity date * České dráhy 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, a district in Seattle * Democratic Republic of the Congo, 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 * "CD", a song by T2 (band) * 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 * Companion dog (title), a title offered to dogs by the American Kennel Club for dog obedience * Cross-dressing, the act of wearing clothing associated with the opposite sex * Corendon Dutch Airlines (IATA code) * Sega Mega-CD ** Sonic CD