A3, A-3, A03 or A.III may refer to:
A3 paper, a paper size defined by ISO 216
Arts and media 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 (A03), in chess, by the Encyclopaedia of Chess Openings code
Music A3, a musical note, 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
Businesses and organizations Military units Kampfgeschwader 200, a special operations unit in World War II 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
Other businesses and organizations Aegean Airlines, by IATA code A³ (A-cubed), an Airbus start-up in the Silicon Valley A3 (TV channel), an Algerian public national television channel also known as Thalitha TV
Science and technology Biology A3 regulatory sequence, a sequence for the insulin gene Adenosine A3 receptor, a human gene Annexin A3, a human gene ATC code A03 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
Computing ARITH-MATIC, as the former name for this programming language Samsung Galaxy A3, a smartphone manufactured by Samsung Electronics Samsung Galaxy A03, a smartphone manufactured by Samsung Electronics Cowon A3, an audio media player
Vehicles and engines Aircraft and aircraft engines A-3 Falcon, a variant of the Curtiss Falcon, an attack aircraft manufactured by the Curtiss Aircraft Company A-3 Skywarrior, a strategic bomber manufactured by Douglas Aircraft Company Abrial A-3 Oricou, a French touring aircraft designed in 1927 Fokker A.III, a 1915 armed version of the Fokker M.5 aircraft RED A03, an aircraft diesel engine by German company Red Aviation GmbH
Automobiles Audi A3, a model of automobile Chery A3, a compact car
Locomotives Bavarian A III, an 1851 German steam locomotive model LNER Gresley Classes A1 and A3, a Pacific locomotive class designed by Sir Nigel Gresley SP&S Class A3, a 1914 steam locomotives class
Rockets and spacecraft 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 Aussat (Optus) A3, a 1987 Australian telecommunication satellite Polaris A-3 missile, an American submarine-launched missile
Watercraft A-3 lifeboat, a 1947 lifeboat carried by the SB-29 Superfortress , a British A-class submarine of the Royal Navy , an A-class submarine of the Spanish Navy , a United States Navy Plunger-class submarine renamed A-3 in 1911
Other uses in science and technology A3, an example of a root system with numerous physical and geometrical applications AUG A3, a variant of the Austrian Steyr AUG rifle A-003, the fourth abort test of the Apollo spacecraft C/2023 A3 (Tsuchinshan–ATLAS) , a comet also called A3 A3 problem solving, a structured problem solving and continuous improvement approach, first employed at Toyota Zeolite A-3, a potassium-type molecular sieve also known as 3A Lely (company) Astronaut A3, the third version of the Astronaut robot manufactured by Lely
Sports A3 (classification), 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 Climbing grade A3
Other uses A3 paper, a paper size defined by ISO 216 A3 roads, in several countries 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. In town and country planning in the United Kingdom, the code for permission to use specific land or premises for restaurants and cafés Biu-Mandara A.3 languages, an Afro-Asiatic family of languages spoken in Cameroon and Nigeria Tonga, by aircraft registration code "Agora! Anarchy! Action!", a slogan for Agorism taken from the New Libertarian Manifesto by Samuel Edward Konkin III
See also 3A (disambiguation) A-Train III, a 1992 computer game M16A3, a variant of the American M16 rifle M60A3, a variant of the American M60 Patton tank A3J, the original designation of the US Navy's A-5 Vigilante bomber