# D3

D3, D03, D.III, D III or D-3 may refer to:

## Transportation
### Roads

* London Buses route D3, a Transport for London contracted bus route
* D3 motorway (Czech Republic), a motorway in the Czech Republic
* D3 road (Croatia), a state road in Croatia
* D3 motorway (Slovakia), a motorway in northern Slovakia

### Aircraft

* Albatros D.III, a 1916 German biplane fighter aircraft
* Dewoitine D.3, a Dewoitine aircraft
* Dunne D.3, a British Dunne aircraft
* Fokker D.III, a 1916 German single-seat fighter aircraft
* Mercedes D.III, a 1914 German 6-cylinder, liquid-cooled inline aircraft engine
* Phönix D.III, a variant of the Austro-Hungarian First World War Phönix D.I biplane fighter
* Pfalz D.III, a 1917 German fighter aircraft
* Schütte-Lanz D.III, a 1918 German fighter aircraft prototype
* Siemens-Schuckert D.III, a 1917 German prototype single-seat fighter aircraft

### Automobiles

* Ford D3 platform, a full-size car automobile platform
* Peugeot D3, a panel van manufactured from 1950 to 1955

### Locomotives

* Bavarian D III, an 1897 steam locomotive model
* LB&SCR D3 class, an 1893 British 0-4-4 tank locomotive design
* GS&WR Class D3, a Great Southern and Western Railway Irish steam locomotive
* GNR Class D3, which was also classified D3 during LNER ownership
* Pennsylvania Railroad class D3, an 1869 American steam locomotive model

### Ships

* HMS Icarus (D03), a 1936 British Royal Navy destroyer
* HMS Ranee (D03), a 1943 British Royal Navy escort aircraft carrier
* USS D-3 (SS-19), a 1910 US Navy submarine
* D3-class motor torpedo boat, a Soviet motor torpedo boat class

## Science and technology

* Dihedral group of order 6 (D$_3$)
* D-brane, a class of p-branes in theoretical physics
* D-3 (video), an uncompressed composite digital video tape format
* Nikon D3, a professional-level digital SLR camera

### Biology and medicine

* ATC code D03 Preparations for treatment of wounds and ulcers, a subgroup of the Anatomical Therapeutic Chemical Classification System
* Dopamine receptor D$_3$, a human gene
* Vitamin D$_3$ (cholecalciferol), a type of Vitamin D
* Melanoma in situ (ICD-10 code: D03)
* Iodothyronine deiodinase type III

### Computing

* d3.js, Data Driven Documents, a JavaScript library for live web graphics based on changing data
* D3, a Pick database sold by Rocket Software
* DOCSIS 3, a cable modem standard

## Entertainment

* D3 Digivice, a device from the fictional anime/manga Digimon series
* D3 (Tenchi Muyo! Ryo-Ohki), a character in the anime Tenchi Muyo!
* D3: The Mighty Ducks, the third film in The Mighty Ducks trilogy
* Dedication 3, a Lil' Wayne and Young Money mixtape
* Dhoom 3, a 2013 Indian Hindi-language action film by Vijay Krishna Acharya, third part of the Dhoom film series
* D3 (film), a 2023 Indian Tamil-language crime thriller by Balaaji

### Video games

* Descent 3, a 1999 computer game
* Diablo III, a 2012 action role-playing game PC game by Blizzard Entertainment
* Dirt 3, a 2011 rallying video game
* Disciples III: Renaissance, a 2009 video game
* Disgaea 3, a 2008/2011 game in the Disgaea series
* Doom 3, a 2004 sci-fi horror first-person shooter computer game
* Driver 3, a 2004 racing, shooting, and adventure video game

## Organizations

* D3 Publisher, a Japanese video game publisher
* Daallo Airlines, (IATA airline code), an airline based in Dubai

## Other uses

* Dublin 3, a Dublin, Ireland postal district
* NCAA Division III, in American collegiate athletics
* USL League One, in American professional soccer, sometimes referred to as USL D3
* d3, a three-sided die in tabletop gaming
* d3, Mieses Opening in chess
* Voiced palato-alveolar affricate (former IPA symbol dʒ), a type of consonantal sound