D4, D.IV, d4 or variants may refer to:

Science and medicine

* 22-Dihydroergocalciferol, vitamin D₄ * D4-isoprostane, a type of isoprostane * ATC code D04, ''Antipruritics, including antihistamines, anesthetics, etc.'', a subgroup of the Anatomical Therapeutic Chemical Classification System * D04, Carcinoma in situ of skin ICD-10 code *

Dopamine receptor D4 The dopamine receptor D4 is a dopamine D2-like G protein-coupled receptor encoded by the gene on chromosome 11 at 11p15.5. The structure of DRD4 was recently reported in complex with the antipsychotic drug nemonapride. As with other dopamine ...

, a human gene * Octamethylcyclotetrasiloxane, called D₄

Mathematics

* Dihedral group of order 4, otherwise known as the

Klein four-group In mathematics, the Klein four-group is a group with four elements, in which each element is self-inverse (composing it with itself produces the identity) and in which composing any two of the three non-identity elements produces the third one. ...

* Dihedral group of order 8, the symmetry group of a regular 4-gon * D₄ (root system)

Technology and computing

D4 (programming language) Dataphor is an open-source truly- relational database management system ( RDBMS) and its accompanying user interface technologies, which together are designed to provide highly declarative software application development. The Dataphor Server has ...

, a programming language of the Dataphor system * D4 video connector, a type of analog video connector found on Japanese consumer electronics * D4 framing standard, a framing standard for traditional time-division multiplexing

Aircraft

* Albatros D.IV, a World War I experimental German fighter aircraft * Auster D.4, a 1960 two-seat British light aircraft * Dewoitine D.4, a

Dewoitine Constructions Aéronautiques Émile Dewoitine was a French aircraft manufacturer established by Émile Dewoitine at Toulouse in October 1920. The company's initial products were a range of metal parasol-wing fighters which were largely ignored by t ...

aircraft *

Dunne D.4 The Dunne D.1, was an experimental tailless aircraft built in the UK in 1907. It comprised a main unit which could be flown as a glider, to which a chassis unit with power train could be added. The glider achieved a short flight in 1907. The D. ...

, a 1907 British experimental aircraft * Fokker D.IV, a World War I German fighter biplane * LFG Roland D.VI, an aircraft powered by the German Mercedes D.III engine * Phönix D.IV, a KuKLFT D-class designation aircraft * Schütte-Lanz D.IV, a 1917 German fighter prototype aircraft * Siemens-Schuckert D.IV, a 1918 German fighter aircraft

Transport

Rail

Bavarian D IV The little D IV was one of the most frequently seen tank locomotives in the stations of the Royal Bavarian State Railways (''Königlich Bayerische Staatsbahn''). The Deutsche Reichsbahn took over almost all of them, 124 in total, of which 24 were ...

, an 1878 German tank locomotive model *

Bavarian D IV (Ostbahn) The Bavarian Class D IV was a German steam locomotive with the Bavarian Eastern Railway (''Bayrische Ostbahn''). These engines had inside frames and Allan valve gear and were delivered in three series, that differed from one another in their di ...

, an 1867 German steam locomotive model * D4, the tank engine variant of the

Victorian Railways Dd class Victorian or Victorians may refer to: 19th century * Victorian era, British history during Queen Victoria's 19th-century reign ** Victorian architecture ** Victorian house ** Victorian decorative arts ** Victorian fashion ** Victorian literatur ...

locomotive in Australia * GSWRI Class D4, a Great Southern and Western Railway Irish steam locomotive *

LNER Class D4 D4, D.IV, d4 or variants may refer to: Science and medicine * 22-Dihydroergocalciferol, vitamin D4 * D4-isoprostane, a type of isoprostane * ATC code D04, ''Antipruritics, including antihistamines, anesthetics, etc.'', a subgroup of the Anatomi ...

, a class of British steam locomotives *

PRR D4 The Pennsylvania Railroad's steam locomotive class D4 (formerly Class C (anthracite), pre-1895) comprised thirty-seven anthracite-burning 4-4-0 locomotives intended for general passenger and freight service on the PRR's New Jersey lines, construc ...

, an 1873 American steam locomotive model *

SP&S Class D-4 The Spokane, Portland & Seattle Railway (SP&S) was a railroad in the northwest United States. Incorporated in 1905, it was a joint venture by the Great Northern Railway and the Northern Pacific Railway to build a railroad along the north bank of ...

, a Spokane, Portland and Seattle Railway locomotive

Road

* D4 motorway (Czech Republic), a motorway in the Czech Republic *

D4 motorway (Slovakia) D4 is a motorway in southwestern Slovakia. The planned highway is commonly referred to as the Bratislava bypass. For decades, there was only a short stretch from Austrian border at Jarovce Jarovce ( hu, Horvátjárfalu, Horvát-Járfalu, hr, H ...

, a motorway in Slovakia

Engines

Mercedes D.IV The Mercedes D.IV was an eight-cylinder, liquid-cooled inline aircraft engine built by '' Daimler Motoren Gesellschaft'' (DMG) and used on a small number of German aircraft during World War I. Design and development The design was based around ...

, a World War I German 8-cylinder, liquid-cooled inline aircraft engine * Mercedes D.IVa, a 1917 German 6-cylinder, water-cooled, inline aircraft engine

Media and entertainment

The D4 The D4 was a rock band from Auckland, New Zealand. Their music was released by Hollywood Records in the U.S., Flying Nun Records in New Zealand and by Infectious Records in the UK. The group was assembled by vocalist/ guitarists Dion Palmer ...

, a rock band from Auckland, New Zealand * '' D4 Princess'', a 1999 Japanese manga series * '' D4: Dark Dreams Don't Die'', a video game by Hidetaka Suehiro for the Xbox One and PC * ''D4'' (film), by Darrin Dickerson * '' D4 - Get Up and Dance'', an Indian dance fiction television series * ''

Diablo IV ''Diablo IV'' is an upcoming action role-playing game developed and published by Blizzard Entertainment, and is the fourth main installment in the '' Diablo'' series. The game was announced on November 1, 2019 at BlizzCon 2019, and is schedule ...

'', an upcoming action role-playing game by Blizzard Entertainment *

Dillinger Four Dillinger Four, sometimes abbreviated as D4, is an American punk rock band formed in 1994 in Minneapolis, Minnesota. They have released four full-length studio albums. Since 1996, the band's lineup has been Patrick Costello on bass guitar and ...

, a punk rock band from Minneapolis, Minnesota

Other uses

Nikon D4 The Nikon D4 is a 16.2-megapixel professional-grade full frame (35mm) digital single-lens reflex camera (DSLR) announced by Nikon Corporation on 6 January 2012. It succeeds the Nikon D3S and introduces a number of improvements including a 16.2 ...

, a flagship DSLR from Nikon * Caterpillar D4 a small crawler type tractor built by Caterpillar Inc. * , a 1949 Australian Navy destroyer * , a 1911 British submarine *

Motorway D4 (Slovakia) D4 is a motorway in southwestern Slovakia. The planned highway is commonly referred to as the Bratislava bypass. For decades, there was only a short stretch from Austrian border at Jarovce to the junction with D2 (part of the former D61), cons ...

, a motorway in southwestern Slovakia * Peugeot D4, a French van sold between 1955 and 1965 *

Dublin 4 Dublin 4, also rendered as D4 and D04, is a historic postal district of Dublin, Ireland including Baggot Street Upper, the southernmost fringes of the Dublin Docklands, and the suburbs of Ballsbridge, Donnybrook, Irishtown, Merrion, Ringsend ...

, a Dublin postcode * d4, a 4-sided die * d4, the second most popular opening move in chess; begins the Queen's Pawn Game * D4, IATA code for Alidaunia airline * D4, commonly used jargon by fans for

Ddu-Du Ddu-Du "Ddu-Du Ddu-Du" (; RR: ''ttuduttudu'') is a song recorded in Korean and Japanese by South Korean girl group Blackpink. It was released on June 15, 2018, through YG Entertainment, in conjunction with the release of the group's first Korean-language ...

, a song produced by K-Pop group

Blackpink Blackpink (, commonly stylized in all caps or as BLɅϽKPIИK) is a South Korean girl group formed by YG Entertainment, consisting of members Jisoo, Jennie, Rosé, and Lisa. The group debuted in August 2016 with their single album '' Square ...