# D2

D2, D02, D.II, D II or D-2 may refer to:

## Places

* Dublin 2, a Dublin, Ireland postcode
* Mount Dulang-dulang, the second highest mountain of the Philippines
* D2, a line of Moscow Central Diameters
* D2 Place One and Two, at Cheung Yue Street and Cheung Shun Street, in Cheung Sha Wan, MTR Lai Chi Kok Station Exit D1 and D2.

### Highways

* D2 motorway (Czech Republic)
* D2 road (Croatia), a state route in Croatia
* D2 motorway (Slovakia)

## Arts & entertainment

* D-2 (mixtape), a 2020 album by South Korean rapper Agust D
* D2: The Mighty Ducks, the second film in The Mighty Ducks trilogy
* R2-D2, a robotic Star Wars character
* "D²", a 2002 episode of Dexter's Laboratory
* D2 (video game), a 1999 game for the Sega Dreamcast
* D2, an abbreviation of the video game Diablo II or Destiny 2
* D2, a sub-group of the Japanese male acting troupe D-Boys
* Dhoom 2, a 2006 Indian Hindi-language action film by Sanjay Gadhvi, second part of the Dhoom film series

## Business

* D2 (hotel chain), owned by Dusit Thani Group
* D2 Mannesmann, the former name of Vodafone's German division, which resulted from the acquisition of the German company Mannesmann AG
* D2 (magazine), published by Dagens Næringsliv
* D2, the IATA code for Damania Airways

## Biology or medicine

* ATC code D02 Emollients and protectives, a subgroup of the Anatomical Therapeutic Chemical Classification System
* Dopamine receptor D$_2$, a protein
* Levuglandin D2
* Prostaglandin D$_2$ receptor, a G-protein coupled receptor
* Resolvin D2
* Cyclin D2 (CCND2)
* Vitamin D$_2$, or ergocalciferol
* D02, the ICD-10 code for carcinoma in situ of middle ear and respiratory system
* DIO2, Type II iodothyronine deiodinase, an enzyme involved in the thyroid system

## Vehicles
### Aircraft

* Albatros D.II, a 1916 German fighter aircraft
* Aviatik (Berg) D.II, a 1917 -Hungarian fighter prototype
* STS-55 or D2, the second German-sponsored Spacelab mission
* Daimler D.II, a Daimler aircraft
* Delta D2, an Australian diesel-powered helicopter design
* Dunne D.2, a British Dunne aircraft
* Euler D.II, a 1917 German single-seat fighter
* Fokker D.II, a WWI German fighter biplane
* Halberstadt D.II, a 1916 German biplane fighter aircraft
* Hughes D-2, a 1943 mysterious American fighter and bomber project
* LFG Roland D.II, a 1917 German single-seat fighter
* Phönix D.II, a variant of the Hungarian First World War biplane fighter D.I
* Schütte-Lanz D.II, a 1915 variant of the German Schütte-Lanz D.I aircraft

### Aircraft engines

* Alfa Romeo D2, a 1931 Italian nine-cylinder radial engine for aircraft use
* Mercedes D.II, a WWI 6-cylinder, liquid-cooled inline aircraft engine

### Locomotives

* Bavarian D II, an 1898 German goods train tank locomotive model
* Bavarian D II (Ostbahn), an 1866 German goods train tender locomotive model
* Bavarian D II (old), an 1873 small tank locomotive
* GS&WR Class D2, a Great Southern and Western Railway Irish steam locomotive
* LB&SCR D2 class, a British locomotive class
* GNR Class D2, a class of British steam locomotives
* PRR D2, an 1868 American steam locomotive model

### Ships

* HMS Attacker (D02), a 1941 American-built escort aircraft carrier
* HMS Devonshire (D02), a 1962 County-class destroyer
* HMS Inglefield (D02), a 1936 I-class destroyer and flotilla leader of the British Royal Navy
* USS D-2 (SS-18), a 1909 American submarine

### Other vehicles

* Char D2, a French tank
* Zhidou D2, a Chinese small electric car

## Electronics

* Cowon D2, a 2007 portable media player with touch screen interface
* Datasaab D2, a Swedish concept computer completed in 1960
* d2, a brand of computer peripherals manufactured by the French firm électronique d2, now trading as LaCie
* D2 kit, a microprocessor development kit MEK6800D2
* D-2 (video), a professional digital video format
* DOCSIS 2, a cable modem standard

## Other uses

* D$_2$, the Codex Claromontanus, a 6th-century Greek-Latin uncial manuscript of the New Testament
* D$_2$, a dihedral group in group theory
* D$_2$, deuterium, an isotope of hydrogen
* D2, an almond-shaped cloud on Neptune
* D2, the code for permission to use specific land or premises for leisure (cinemas, swimming baths, gymnasiums) in town and country planning in the United Kingdom
* D2, the Double Dragon hacking group
* Division II (disambiguation), in sports leagues, etc.
* Marcelo D2 (born 1967), Brazilian rapper
* D2, an abbreviation for DOCSIS 2.0, an international telecommunications standard
* D2 steel, a type of D-Grade tool steel with good wear resistance commonly found in shears and high-end knives
* D2, gaming notation for a 2-sided die, such as a coin
* D2, a standard paper size between B2 and A1
* D2 Subway, a planned Dallas, Texas light rail tunnel