D (disambiguation)

D is the fourth letter of the Latin alphabet.

D or d may also refer to:

Places

 * D River, in Oregon, US
 * Detroit, US (nickname "D")

People with the name

 * D, the bass player for Australian band Testeagles
 * "D!" or "Dee!", names of Detlef Soost, a German dancer and choreographer
 * D, nickname of Indian actor Darshan (Kannada actor)
 * D, nickname of Indian actor Dhanush (cf. D50 (film))

Fictional entities

 * D, a character in a series of novels titled Vampire Hunter D by Hideyuki Kikuchi
 * D, a nickname given to Count Dracula in the novel Dracula written by Bram Stoker
 * D, one of the characters in Another Code: Two Memories (Trace Memory)
 * Count D, a character in the anime/manga series Pet Shop of Horrors
 * Substance D, a fictional recreational drug in the novel and film A Scanner Darkly

Games

 * D (video game), a game released in 1995 for the PC, 3DO, PlayStation and Sega Saturn

Groups and labels

 * D (band), a Japanese rock/metal band
 * D Records, a former record label in Houston, Texas, US
 * "d:" or "d:?", often used to refer to the Christian rock band Delirious?
 * "The D", one of the names of comedy rock band Tenacious D

Albums

 * D (Deuter album), 1971
 * D (Os Paralamas do Sucesso album), 1987
 * D (White Denim album), 2011
 * D (single album), by Big Bang, 2015
 * D, followed by a number, a composition by Franz Schubert according to the Schubert Thematic Catalogue
 * Substance D, a drum and bass compilation album by Dieselboy
 * D, by Daryl Hall, 2024

Other uses in music

 * D (musical note)
 * D major, a scale
 * D major chord; See Chord names and symbols
 * D minor, a scale
 * Steinway D-274 or D, a concert grand piano model manufactured by Steinway & Sons
 * "D", a song by Little River Band from their album Playing to Win

Periodicals

 * D, a weekly supplement to the Italian newspaper la Repubblica
 * D Magazine, a magazine for the city of Dallas, Texas, US

Other uses in arts, entertainment, and media

 * D (film), a 2005 Bollywood film
 * Initial D, a 1995 Japanese manga and anime about mountain drifting that has spawned several arcade and console games
 * D, the production code for the 1964 Doctor Who serial Marco Polo
 * "D" Is for Deadbeat, the fourth novel in Sue Grafton's "Alphabet mystery" series, published in 1987
 * The D logo for the Russian television channel Domashny

Business and economics

 * Demand (D), in economics
 * Dominion Resources (New York Stock Exchange ticker symbol D)
 * Federal Reserve Bank of Cleveland (serial numbers of United States dollars, beginning with D)
 * Penny (British pre-decimal coin) (d)

Computing

 * .d, a file format used for Agilent MassHunter mass spectrometry software
 * .d, a pathname component suffix for a directory; for example with the init program
 * -d, a suffix of a daemon, a computer program that runs as a background process
 * D - Minimal Protection, a security division in the Trusted Computer System Evaluation Criteria

Programming languages

 * D (programming language), a C++-like programming language developed by Walter Bright
 * D, a programming language designed to be used with the DTrace dynamic tracing framework

Other uses in technology

 * D, Mitsubishi Electric's mobile phones in Japan
 * D battery, a standard size dry cell battery in electronics
 * d', sensitivity index, a statistic used in signal detection theory

Linguistics

 * ’d, a contraction of the English words had and would
 * Dingir (D), the Sumerian sign for deity
 * [d] or /d/, Voiced alveolar stop consonant in the International Phonetic Alphabet

Measurements

 * d, deci-, SI prefix factor 0.1

Astronomy and Earth science

 * D, a February 16 through 29 discovery in the provisional designation of a comet or asteroid
 * D, for "Degenerate", a white dwarf in stellar classification
 * D/, for "destroyed/disappeared" in comet nomenclature
 * D region, part of the ionosphere

Mathematics

 * D, 500 in Roman numerals
 * D, Thirteen, or D in hexadecimal and other positional numeral systems with a radix of 14 or greater
 * D and d, the derivative operators
 * d, the symbol for the total differential operator; in a related but more general meaning, it is the exterior derivative operator in differential geometry
 * d, often a variable for the diameter of a circle in geometry
 * d(n), Divisor function, the number of positive divisors of an integer n
 * $$\mathbb{D}$$ in blackboard bold, the unit disk in the complex plane, or the decimal fractions; see Number
 * Cohen's d, a statistical measure of effect size.

Biology, chemistry, and medicine

 * D, Aspartic acid, in biochemistry
 * D (or Asp), an abbreviation for the amino acid aspartate
 * D, Diarrhea
 * D, deuterium, an isotope of hydrogen
 * d, Deuteron, the nucleus of deuterium
 * D- prefix, a dextrorotatory compound
 * ATC code D Dermatologicals, a section of the Anatomical Therapeutic Chemical Classification System
 * Haplogroup D (mtDNA), a human mitochondrial DNA (mtDNA) haplogroup
 * Haplogroup D-M174, a Y-chromosomal DNA (Y-DNA) haplogroup
 * Vitamin D

Physics

 * D, Debye (D), a unit of electrical dipole moment
 * D, Dioptre (D), a unit of measurement of the optical power of a lens or curved mirror (also in Medicine)
 * D, Diffusion coefficient (D), in molecular physics
 * D, Electric displacement field (D)
 * D meson, mesons containing charm quarks in particle physics
 * d, thickness, diameter, relative density, lattice plane spacing, and degeneracy of vibrational mode, in molecular spectroscopy
 * D band (disambiguation)

Solid state physics

 * D(E), a function of energy
 * Debye–Waller factor (D)
 * Diode (D), an electronic component
 * Wavenumber [D(k)], a symbol for the density of states

Time

 * Day (d), in metrology
 * December (D), in calendars
 * Dominical letter D, for a common year starting on Thursday

Transportation

 * D (Los Angeles Railway), a line operated by the Los Angeles Railway, US
 * D (New York City Subway service), US
 * D Line (Los Angeles Metro), US
 * Drive, or D, the forward cruising gears in an automatic transmission
 * Tesla Model D, a concept all-wheel drive electric sedan
 * Line D of the Buenos Aires Subte
 * JRW kinki-D.svg, the official West Japan Railway Company service symbol for the JR West Nara Line.

Other uses

 * D (grade), a below average grade in education
 * D, a brassiere cup size
 * d, the number of sides of dice in role-playing games
 * d, the common US measurement of the penny size (an approximation of length), of a nail
 * D-Company, a criminal group
 * Daughter (d)
 * Defense (sports) (D)
 * Democrat (D), a member of the US Democratic Party
 * Denarius, a Roman coin
 * Died (d.)
 * Dominant person (D/), in dominance and submission
 * Delta, the military time zone code for UTC+04:00
 * D, the international license plate code for Germany (Deutschland)