D3

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

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

Science and technology

 * Dihedral group of order 6 (D3)
 * 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 D3, a human gene
 * Vitamin D3 (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