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Double-decker bus
A double-decker bus is a bus with two passenger decks, seating 60 to 120 people. The red London double-decker is among the most recognizable vehicles in the world.
Double-ended queue
A double-ended queue, abbreviated deque, is a data structure in which elements can be added, removed, and examined at both the front and the back.
Double-enveloping worm gear
A double-enveloping worm gear, also called globoidal or double-throated gearing, is a worm drive in which the hourglass-shaped worm and wheel wrap around each other for high torque capacity.
Double-shield tunnel boring machine
A double-shield tunnel boring machine is a hard-rock TBM whose telescopic two-shield body lets boring and segmental lining erection proceed simultaneously, patented by SELI and Robbins in 1971.
Double-skin facade
A double-skin facade (DSF) is a building envelope with two layers of glazing separated by a ventilated cavity that buffers solar heat, noise, and ventilation before air reaches the interior.
Double-spending
Double-spending, also called a double spend, is spending the same digital money more than once, the central security problem electronic cash and blockchain payments must prevent.
Double-stack rail transport
Double-stack rail transport loads intermodal shipping containers two high on well cars, roughly doubling containers carried per railcar and cutting crews, fuel, and train paths.
DoubleClick
DoubleClick, also known as DoubleClick Inc., was an American internet advertising company founded in 1996, best known for its DART ad serving platform and its 2008 acquisition by Google.
DoubleDown Interactive
DoubleDown Interactive is a Seoul-based South Korean developer of social casino games, majority-owned by DoubleU Games; its flagship DoubleDown Casino launched on Facebook in 2010.
DoubleVerify
DoubleVerify is an American software company that verifies digital advertising, checking that ads reach real people in brand-suitable content. Founded in 2008, it is headquartered in New York.
Doubly linked list
A doubly linked list is a linked data structure whose nodes hold pointers to both the next and previous elements, allowing backward traversal and constant-time deletion.
Doubly-fed induction generator
The doubly-fed induction generator (DFIG) is a wind turbine generator whose rotor is fed through a partially rated converter, allowing variable-speed operation at low converter cost.
Doudna (supercomputer)
Doudna is the next flagship supercomputer of the National Energy Research Scientific Computing Center at Lawrence Berkeley National Laboratory, announced in 2025, built by Dell and NVIDIA, and named for Nobel laureate Jennifer Doudna.
Doug Cutting
Doug Cutting (born 1961), American software engineer and Stanford graduate, founder of Apache Lucene, Nutch, Hadoop, and Avro; Hadoop creator at Yahoo!, later Cloudera chief architect and former ASF board chairman.
Douglas A-1 Skyraider
The Douglas A-1 Skyraider, also called the AD Skyraider, was a single-engine, propeller-driven attack aircraft of the United States Navy that served from 1946 into the Vietnam War.
Douglas A-20 Havoc
The Douglas A-20 Havoc, called the Boston in British service, was an American twin-engine light bomber of World War II, with 7,385 built between 1940 and 1944.
Douglas A-26 Invader
The Douglas A-26 Invader, also called the B-26 Invader, is an American twin-engine attack bomber that flew combat in World War II, Korea, and Vietnam.
Douglas A-3 Skywarrior
The Douglas A-3 Skywarrior, also known as the A3D, is a jet-powered strategic bomber Douglas built for the US Navy, first flown in 1952 and retired in 1991.
Douglas A-4 Skyhawk
The Douglas A-4 Skyhawk, originally designated A4D, is a single-seat, carrier-capable light attack aircraft built by Douglas, first flown in 1954 and flown heavily in Vietnam.
Douglas A2D Skyshark
The Douglas A2D Skyshark was a turboprop-powered carrier-based attack aircraft Douglas built for the US Navy as a planned successor to the AD Skyraider, canceled in 1954.
Douglas AC-47 Spooky
The Douglas AC-47 Spooky was the first operational fixed-wing gunship of the United States Air Force, a C-47 cargo plane fitted with side-firing miniguns in Vietnam.
Douglas Aircraft Company
The Douglas Aircraft Company was an American aircraft manufacturer founded in 1921, known for the DC-3 airliner and C-47 transport before merging with McDonnell in 1967.
Douglas B-18 Bolo
The Douglas B-18 Bolo, built as the DB-1, was an American twin-engine medium bomber derived from the DC-2 transport and the Air Corps' primary bomber into 1941.
Douglas B-23 Dragon
The Douglas B-23 Dragon was an American twin-engine medium bomber built by Douglas Aircraft, 38 produced in 1939 and 1940, used in training and transport roles but never in combat.
Douglas B-66 Destroyer
The Douglas B-66 Destroyer is a US Air Force twin-engine jet tactical bomber and reconnaissance aircraft adapted from the Navy's A3D Skywarrior in the 1950s.
Douglas B. Lenat
Douglas B. Lenat, also known as Douglas Bruce Lenat, was an American AI researcher who created AM and Eurisko and led the Cyc commonsense project until his death in 2023.
Douglas Bader
Douglas Bader was a Royal Air Force flying ace of the Second World War who returned to combat flying despite losing both legs in a 1931 air crash.
Douglas C-124 Globemaster II
The Douglas C-124 Globemaster II was an American four-engine strategic cargo aircraft built by Douglas, the US Air Force's primary heavy-lift transport of the 1950s and early 1960s.
Douglas C-47 Skytrain
The Douglas C-47 Skytrain, also known as the Dakota, is a twin-engine military transport derived from the DC-3 airliner, used by the US military from 1941.
Douglas C-54 Skymaster
The Douglas C-54 Skymaster, designated R5D by the Navy, was a four-engine American military transport that served in World War II, the Berlin Airlift, and the Korean War.