D5 can refer to: · D5 All Things Digital conference in Silicon Valley · D5 HD, a professional digital video format · Highway D5 in the Czech Republic · Volvo D5 engine · Dau Air (IATA code D5) · D5 dopamine receptor subtype · D5 class Klingon starship, in the Star Trek science fiction series · D5 tank gun, a derivative of the 85 mm air defense gun M1939 · Detour for the M5 South Western Motorway, Sydney, Australia · The Trident missile system, currently deployed as Trident-II D5 D5D5D5D5