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 In astronomy, Durchmusterung or Bonner Durchmusterung (BD) is an astrometric star catalogue of the whole sky, compiled by the Bonn Observatory in Germany from 1859 to 1903. The name comes from ('run-through examination'), a German word used for ...

, a star catalog of the southern sky *

Cosmological decade A cosmological decade (CÐ) is a division of the lifetime of the cosmos. The divisions are logarithmic in size, with base 10. Each successive cosmological decade represents a ten-fold increase in the total age of the universe. As expressed in l ...

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