A3, A03 or A.III may refer to: *

A3 paper ISO 216 is an International Organization for Standardization, international standard for paper sizes, used around the world except in North America and parts of Latin America. The standard defines the "A", "B" and "C" series of paper sizes, wh ...

, a paper size defined by ISO 216

Biology

* A3 regulatory sequence, a sequence for the insulin gene * Adenosine A₃ receptor, a human gene * Annexin A3, a human gene *

ATC code A03 A03A Drugs for functional gastrointestinal disorders A03AA Chemical synthesis, Synthetic anticholinergics, esters with Tertiary amine, tertiary amino group :A03AA01 Oxyphencyclimine :A03AA03 Camylofin :A03AA04 Mebeverine :A03AA05 Trimebutine :A0 ...

''Drugs for functional gastrointestinal disorders'', a subgroup of the Anatomical Therapeutic Chemical Classification System * Brachydactyly type A3, a disease * British NVC community A3 (Spirodela polyrhiza - Hydrocharis morsus-ranae community), a British Isles plants community * Gibberellin A3, a plant hormone * HLA-A3, a Human MHC Serotype HLA-A * Subfamily A3, a rhodopsin-like receptors subfamily * Urea transporter A3, a trans-membrane protein

Games

* '' A3!'', a Japanese video game and multimedia franchise * A3 - Assault on the Aerie of the Slave Lords, a 1981 module for the Dungeons & Dragons fantasy role-playing game * Alpha Trion, as the former name of this character from the Transformers Series *

Bird's Opening Bird's Opening (or the Dutch Attack) is a chess opening characterised by the move: : 1. f4 Named after 19th century English player Henry Bird, Bird's opening is a standard flank opening. White's strategic ideas involve control of the e5-squa ...

(A03), in chess, by the Encyclopaedia of Chess Openings code

Music

* A3, a

musical note In music, notes are distinct and isolatable sounds that act as the most basic building blocks for nearly all of music. This musical analysis#Discretization, discretization facilitates performance, comprehension, and musical analysis, analysis. No ...

, the A below Middle C * Alabama 3, a band known as A3 in the U.S. to avoid confusion with the country group Alabama * A-3, a Yamaha musical instrument product

Sports

A3 (classification) A3 is an amputee sport classification used by the International Sports Organization for the Disabled (ISOD) for people with acquired or congenital amputations. A3 classified sportspeople have both legs amputated below knee. Their amputations im ...

, an amputee sport classification * A3 Champions Cup, a club football tournament also known as the East Asian Champions Cup * Arrows A3, a 1980 racing car * A3, a climbing grade

Vehicles

* A-3 lifeboat, a 1947 lifeboat for carrying by the SB-29 Superfortress * Abrial A-3 Oricou, a French touring aircraft designed in 1927 *

Audi A3 The Audi A3 is a small family car (C-segment) manufactured and marketed by the German automaker Audi, Audi AG since September 1996. The first two generations of the Audi A3 were based on the Volkswagen Group A platform, while the third and fo ...

, a model of automobile *

Aussat (Optus) A3 This is a list of the satellites operated by Optus, an Australian telecommunications company. The satellite communications facility is located at Belrose on Sydney's Northern Beaches. Optus' satellites are divided into 4 classes A, B, C and D. As ...

, a 1987 Australian telecommunication satellite *

Bavarian A III The Bavarian A III 2-2-2 engines were German steam locomotives in service with the Royal Bavarian State Railways (''Königlich Bayerische Staatsbahn''). Once again these engines were used to experiment with a short boiler and Meyer expansion v ...

, an 1851 German steam locomotive model *

Chery A3 The Chery A3 is a compact car built by the Chinese manufacturer Chery between 2008–2015, offered as a 4-door sedan and as a 5-door hatchback. It was revealed for the first time as a concept car at the 2006 Beijing Motor Show and production ca ...

, a compact car *

LNER Gresley Classes A1 and A3 The London and North Eastern Railway Gresley Classes A1 and A3 were "Pacific" steam locomotives designed by Nigel Gresley for passenger work. They were initially intended for use on the Great Northern Railway (Great Britain), Great Northern Ra ...

, a Pacific locomotive class designed by Sir Nigel Gresley *

SP&S Class A3 Spokane, Portland and Seattle Railway's Class A-3 was a class of 0-6-0 steam locomotive A steam locomotive is a locomotive that provides the force to move itself and other vehicles by means of the expansion of steam. It is fuelled by burn ...

, a 1914 steam locomotives class

Weapons and military

* A-3 Falcon, a variant of the

Curtiss Falcon The Curtiss Falcon was a family of military biplane aircraft built by the American aircraft manufacturer Curtiss Aeroplane and Motor Company during the 1920s. Most saw service as part of the United States Army Air Corps as observation aircraft ...

, an attack aircraft manufactured by the Curtiss Aircraft Company *

A-3 Skywarrior The Douglas A-3 Skywarrior is a jet propulsion, jet-powered strategic bomber that was developed and produced by the Douglas Aircraft Company. It was designed by Douglas on behalf of the United States Navy, which sought a aircraft carrier, carr ...

, a strategic bomber manufactured by Douglas Aircraft Company * AUG A3, a variant of the Austrian Steyr AUG rifle * Fokker A.III, a 1915 armed version of the Fokker M.5 aircraft * HMS ''A3'', a British A-class submarine of the Royal Navy * ''Kampfgeschwader'' 200, from its historic ''Geschwaderkennung'' code with the Luftwaffe in World War II * Polaris A-3 missile, an American submarine-launched missile * Wendes Artillery Regiment, a former Swedish Army artillery regiment, by designation * A3, the staff designation for air force headquarters staff concerned with operations ** A3 Air Operations Branch, of the Joint Force Air Component Headquarters UK * USS ''Grampus'' (SS-4), a ''Plunger''-class submarine of the United States Navy * Aggregate 3, the 3rd design in the Aggregate family of rockets, precursor to the V-2 rocket, developed by the Germans during World War II

Other uses

* A₃, an example of a

root system In mathematics, a root system is a configuration of vector space, vectors in a Euclidean space satisfying certain geometrical properties. The concept is fundamental in the theory of Lie groups and Lie algebras, especially the classification and ...

with numerous physical and geometrical applications * A-3 visa, a document given to employees of A-1 and A-2 Visa Holders who are representing a foreign government inside the U.S. * A3, the code for permission to use specific land or premises for restaurants and cafés in

town and country planning in the United Kingdom Town and country planning in the United Kingdom is the part of UK land law which concerns land use planning. Its goal is to ensure sustainable economic development and a better environment. Each country of the United Kingdom has its own planni ...

* A3 roads, in several countries * A-003, the fourth abort test of the Apollo spacecraft * Biu-Mandara A.3 languages, an Afro-Asiatic family of languages spoken in Cameroon and Nigeria * Comet A3 also known as C/2023 A3 (Tsuchinshan–ATLAS) * Cowon A3, an audio media player * Aegean Airlines, by IATA code *

Tonga Tonga, officially the Kingdom of Tonga, is an island country in Polynesia, part of Oceania. The country has 171 islands, of which 45 are inhabited. Its total surface area is about , scattered over in the southern Pacific Ocean. accordin ...

, by aircraft registration code * ARITH-MATIC, as the former name for this programming language * "Agora! Anarchy! Action!", a slogan for Agorism taken from the '' New Libertarian Manifesto'' by Samuel Edward Konkin III * A3 problem solving, a structured problem solving and continuous improvement approach, first employed at Toyota * Samsung Galaxy A3, a smartphone manufactured by Samsung Electronics * Samsung Galaxy A03, a smartphone manufactured by Samsung Electronics * A³ (A-cubed), an

Airbus Airbus SE ( ; ; ; ) is a Pan-European aerospace corporation. The company's primary business is the design and manufacturing of commercial aircraft but it also has separate Airbus Defence and Space, defence and space and Airbus Helicopters, he ...

start-up in the Silicon Valley *

A3 (TV channel) TV3 (in ), also known as El Ikhbariya (in ) and formerly Algeria 3 (or simply A3), is the third Algeria Algeria, officially the People's Democratic Republic of Algeria, is a country in the Maghreb region of North Africa. It is bordered to ...

, an Algerian public national television channel also known as Thalitha TV * RED A03, an aircraft diesel engine by German company Red Aviation GmbH * Zeolite A-3, a potassium-type molecular sieve also known as 3A.