List of acronyms: A
(Main list of acronyms)
A0–9
- A1C – Airman First Class
- A2ATD or A2ATD – Anti-Armour Advanced Technology Demonstration
- A2C2 or A2C2 – Army Airspace Command and Control
- A3 – many, including a European larger than standard office paper size
- A4 – many, including a European standard office paper size; see entry
- A10 – Atlantic 10 Conferencee
AA
- aa – Afar language
- aA – Attoampere
- AA
- * achieved availability
- * Alcoholics Anonymous
- * Armed Forces Americas
- * Aruba
- * assembly area
- * Automobile Association
- * avenue of approach
- * American Airlines
- * Aerolíneas Argentinas
- AAA
- * administration, authorization, and authentication
- * American Automobile Association
- * anti-aircraft artillery
- * Amateur Athletic Association
- * Asistencia Asesoría y Administración
- AAAI – Association for the Advancement of Artificial Intelligence, formerly American Association for Artificial Intelligence
- AAAS – American Association for the Advancement of Science
- AAAV – Advanced Amphibious Assault Vehicle
- AABN – African Aurora Business Network
- AABP – American Association of Bovine Practitioners
- AAC
- * American Athletic Conference
- * Army Air Corps
- AACL – Albanian American Civic League
- AACCS – American Association of Christian Colleges and Seminaries
- AAD
- * analogue-analogue-digital
- * Australian Antarctic Division
- AADHD – Adult attention deficit hyperactivity disorder
- AADT – annual average daily traffic
- AADAC – Alberta Alcohol and Drug Abuse Commission
- AADC
- * area air defense commander
- * amino acid decarboxylase
- * aromatic L-amino acid decarboxylase
- * Australian Antarctic Data Centre
- AAFC
- * U.S. Army Air Corps Ferrying Command
- * Football Conference
- AAFES – Air Force Exchange Service
- AAI – applied artificial intelligence
- AAIS – advanced airborne interceptor simulator
- AAM – air-to-air missile
- AAMOF – as a matter of fact
- AAN – American Academy of Nursing
- AANEAS – Anglo-Australian Near-Earth Asteroid Survey
- AAODL – Atmospheric Aerosols and Optics Data Library
- a.a.p. – Associated Artists Productions
- AAP
- * advanced acquisition plan
- * Allied administrative publication
- * American Academy of Pediatrics
- AAPC – Accounting and Auditing Policy Committee
- aar – Afar language
- AAR
- * after-action review
- * Association of American Railroads
- AARP – American Association of Retired Persons
- AAS
- * Advanced Automation System
- * American Astronomical Society
- AASPEM – advanced air-to-air system performance evaluation model
- AAT – Australian Antarctic Territory
- AAV – Amphibious Assault Vehicle
- AAWC – anti-air warfare commander
AB
- ab – Abkhaz language
- AB
- * Able Seaman
- * Alberta
- ABA
- * Adriatic Basketball Association
- * American Bar Association
- * American Basketball Association
- * American Beverage Association
- * American Bicycle Association
- * American Birding Association
- * Australian Broadcasting Authority
- ABB – ASEA Brown Boveri
- ABBA – Agnetha, Benny, Björn, Anni-Frid
- ABC
- * abstinence, be faithful, condoms
- * Active Body Control
- * airway, breathing, circulation
- * Alcoholic Beverage Control
- * alien big cat
- * always be careful
- * American Bird Conservancy
- * American-born Chinese
- * American Broadcasting Company
- * anti-lock brake controller
- * Associated British Cinemas
- ** ABC Cinemas
- ** ABC Weekend TV
- * Associated British Corporation
- * Atanasoff–Berry Computer
- * Atlantic Baptist College
- * atomic, biological, chemical
- * Australian Broadcasting Corporation
- * already been chewed gum
- ABCA
- * American, British and Canadian Armies
- * Army Bureau of Current Affairs
- ABCS – Army Battle Command System
- ABET – Accreditation Board for Engineering and Technology
- ABFIST – Advanced Bradley Full Crew Interactive Skills Trainer
- ABGI – Addington-Barker Group International
- ABIN – Agência Brasileira de Inteligência
- abk – Abkhaz language
- ABL – American Basketball League
- ABLE
- * Achieving a Better Life Experience Act, a U.S. law that established tax-advantaged accounts for the benefit of individuals with disabilities
- * AirBorne Law Enforcement
- ABM – anti-ballistic missile – Asynchronous Balanced Mode – automated banking machine
- ABMC – American Battle Monuments Commission
- ABN
- * Australian Business Number
- * Advance Beneficiary Notice of Non-coverage
- ABPI – Association of the British Pharmaceutical Industry
- ABRSM – Associated Board of the Royal Schools of Music
- ABS
- * acrylonitrile butadiene styrene
- * anti-lock braking system
- ABSA – Amalgamated Banks of South Africa
- ABSTRIPS – abstraction-based STRIPS
- ABV – Alcohol by volume
- ABW – Aruba
AC
- aC – Attocoulomb
- Ac – Actinium
- AC
- * Adriamycin-Cyclophosphamide
- * Air Conditioning
- * Aircraftman
- * Alternating Current
- * Altocumulus
- * ante Christum
- * ante cibum
- * Antigua and Barbuda
- * Associazione Calcio
- A/C – Air Conditioned/Conditioning – Aircraft
- AC1 – Aircraftman 1st Class
- AC2 – Aircraftman 2nd Class
- ACA
- * Affordable Care Act, shorthand for the Patient Protection and Affordable Care Act, commonly called "Obamacare"
- * Airspace Control Authority
- * Airspace Co-ordination Area
- * A Current Affair
- ACAB, short for "All Cops Are Bastards"; used as a political slogan associated with dissidents who are opposed to the police.
- ACARS – Aircraft Communications Addressing and Reporting System
- ACAS
- * Aboriginal Children's Advancement Society
- * Advisory, Conciliation and Arbitration Service
- ACB – Asociación de Clubes de Baloncesto
- ACC
- * U.S. Air Combat Command
- * Air Component Commander
- * Alpine Club of Canada
- * Altocumulus castellanus
- * Area control center
- * Atlantic Coast Conference
- * Automatic climate control
- ACCA
- * The Association of Chartered Certified Accountants
- * Automatic Cloud Cover Assessment
- ACCAC – Awdurdod Cymwysterau, Cwricwlwm ac Asesu Cymru
- ACCD – American Coalition of Citizens with Disabilities
- ACCS – Air Communications and Control Squadron
- ACDA – Arms Control & Disarmament Agency
- ACDC
- * Alternating Current Direct Current
- * [AC/DC|the name of AN (disambiguation)|an Australian rock music band]
- * a term for a bisexual person
- A/Cdre – Air Commodore
- ACDT
- * Apple Certified Desktop Technician
- * Australian Central Daylight Time
- ACE
- * Air Combat Emulator
- * Allied Command Europe
- * Angiotensin-converting enzyme
- * Armored Combat Earthmover
- * Automatic Computing Engine
- ACE2 – Angiotensin-converting enzyme 2
- ACES
- * Aerolíneas Centrales de Colombia
- * Auxiliary Campus Enterprises and Services of Alfred State College
- ACF
- * Administration for Children and Families
- * American Car and Foundry
- * American Culinary Federation
- ACH – Automated clearing house
- ACHT – Average Call Hold Time
- ACID – Atomicity, Consistency, Isolation, and Durability
- ACINT – Acoustic Intelligence
- ACK – Acknowledge
- ACL
- * Access Control List
- * Anterior cruciate ligament; the initialism can also refer to an injury to this ligament
- * Atlantic Coast Line Railroad
- ACLJ – American Center for Law and Justice
- ACLOS – Automatic CLOS
- ACLS – American Council of Learned Societies
- ACLU
- * American Civil Liberties Union
- * American Communist Lawyers Union
- ACM – many, including Association for Computing Machinery; see entry
- ACMC – Assistant Commandant of the Marine Corps
- ACN
- * Airborne Communications Node
- * Australian Company Number
- ACNA
- * Anglican Church in North America
- * ACNA (company) - National Dyes Company and Affiliates
- ACO – Airspace Control Order
- ACOBA – Advisory Committee on Business Appointments
- ACOG – American College of Obstetricians and Gynecologists
- ACOM – Atlantic Command
- ACORN – Association of Community Organizations for Reform Now
- ACP
- * African, Caribbean and Pacific Group of States
- * Air Control Point
- ACR – Advanced Concepts and Requirements
- ACRI – African Crisis Response Initiative
- ACRT – Advanced Concepts Research Tool simulator
- ACS
- * Affiliated Computer Services
- * Alaska Communications Service
- * American Cancer Society
- * American Chemical Society
- * Association of Caribbean States
- * Australian Computer Society
- ACSC – Army Command and Staff College
- ACST – Australian Central Standard Time
- ACST – American Cooperative School of Tunis
- ACT
- * Adaptive Control of Thought
- * American College Test (ing Program)
- * Australian Capital Territory
- ACT UP – AIDS Coalition to Unleash Power
- ACTD – Advanced Concept Technology Demonstration
- ACTF
- * Army Constructive Training Federation
- * Australian Children's Television Foundation
- ACT-R – ACT-Rational
- ACT-R/PM – ACT-R/Perceptual-Motor
- ACTU – Australian Council of Trade Unions
- ACU
- * Abilene Christian University
- * American Conservative Union
- ACUF
- * BGN Advisory Committee on Undersea Features
- * American Conservative Union Foundation
- ACV – Armoured Combat Vehicle
AD
- AD – Air Defence – Andorra – Anno Domini
- A/D – Analog/Digital
- ADA
- * Air Defence Artillery
- * American Dental Association
- * Assistant District Attorney
- * Americans with Disabilities Act
- * ADA Cryptocurrency token for Cardano blockchain
- ADAC – Allgemeiner Deutscher Automobil-Club
- ADAGE – Air Defense Air to Ground Engagement
- ADAP – AIDS Drug Assistance Program
- ADAS – Asiago-DLR Asteroid Survey
- ADAT – Alesis Digital Audio Tape
- ADatP – Automated Data Processing
- ADATS –
- * Agricultural Development and Training Society
- * Air Defence Anti-Tank System
- * Australian Defence Air Traffic System
- ADB – Asian Development Bank
- ADB- All da best/All the best - texting slang
- ADC –
- * Aide De Camp
- * U.S. Air Defense Command
- * Apple Display Connector
- ADCTS – Advanced Distributed Combat Training System
- ADD –
- * Analog Digital Digital
- * Attention-Deficit Disorder
- * Administration on Developmental Disabilities
- ADDIE – Analyze Design Develop Implement and Evaluate
- ADDNS – Advanced Deployable Day/Night Simulation
- ADE
- * Algebraic differential equation
- * Antibody-dependent enhancement
- ADF
- * Australian Defence Force
- * African Development Foundation
- ADGB – Air Defence of Great Britain
- ADHD – Attention-Deficit Hyperactivity Disorder
- ADHS – Attention-Deficit Hyperactivity Syndrome
- ADI – Acceptable/Allowable Daily Intake
- ADIZ – Air Defence Identification Zone
- ADL – Anti-Defamation League
- ad loc. – ad locum
- ADM –
- * Administrative
- * Admiral, and the U.S. Public Health Service Commissioned Corps
- * Archer Daniels Midland
- * Assistant Deputy Minister
- ADOA – Air Defence Operations Area
- ADP –
- * Adenosine DiPhosphate
- * Army Doctrine Publication
- * Automatic/Automated Data Processing
- ADRG – Arc-second Raster Chart Digitized Raster Graphics
- ADS –
- * Active Denial System
- * Astrophysics Data System
- * Attention Deficit Syndrome
- ADSR – Attack, Decay, Sustain, Release
- ADT
- * Abu Dhabi Terminals, operator of commercial ports in Abu Dhabi
- * American District Telegraph, a former name of ADT Inc.
- * Atlantic Daylight Time
- ADTB – Army Doctrine and Training Bulletin
- adv. – adversus
- ADW – Air Defence Warning
AE
- ae – Avestan language
- AE
- * Armed Forces Africa/Canada/Europe/Middle East
- * United Arab Emirates
- * Artix Entertainment
- * American Eagle
- A&E
- * Arts & Entertainment Network, the original name for the U.S. TV channel now known as A&E Network
- * Accident and Emergency
- AEB – Autonomous Emergency Braking, see Collision avoidance system
- AED – United Arab Emirates dirham
- AEDT – Australian Eastern Daylight Time
- AEF – American Expeditionary Force
- AEGIS – Airborne Early warning Ground environment Interface Segment
- AEI-T – Army Enterprise Infostructure-Transport
- aeq. – aequalis
- AESR – Aeronautical Equipment Service Record
- AEST – Australian Eastern Standard Time
- aet. – aetatis
- aet – After extra time
- AEW
- * Air Expeditionary Wing
- * Airborne early warning
- * Airborne electronic warfare
- * All Elite Wrestling
AF
- af – Afrikaans language
- aF – Attofarad
- AF
- * Afghanistan
- * Air Force
- * As fuck
- AFA
- * U.S. Air Force Academy
- * Asociación del Fútbol Argentino
- AFAIC – As Far As I'm Concerned
- AFAICT – As Far As I Can Tell
- AFAIK – As Far As I Know
- AFAIR – As Far As I Remember/Recall
- AFAM
- * Associazione Friulana di Astronomia e Meteorologia
- * Department of African and Afro-American Studies, University of North Carolina at Chapel Hill — notable for its links to the school's academic-athletic scandal in the 2010s
- AFATDS – Advanced Field Artillery Tactical Data System
- AFC
- * American Football Conference
- * Approved for construction
- * Asian Football Confederation
- AFCEA – Armed Forces Communications and Electronics Association
- AfD
- * Allianz für Deutschland, former political alliance in East Germany
- * Alternative für Deutschland, current German political party
- AFD
- * Active Format Description, a technical standard for TV or set-top box decoders
- * Advanced Format Drive, a type of computing storage device
- * Adjustable-frequency drive
- * Adult Film Database, web-based database of adult cinema
- * Agence française de développement, a French international development agency
- * Alliance des forces démocratiques, an Ivorian political alliance
- * Alliance for Freedom and Democracy, an Eritrean political party
- AFDB – African Development Bank
- AFES – Automatic Fire Extinguishing System
- AFG – Afghanistan
- AFGAM – Amazon Facebook Google Apple Microsoft
- AFI
- * French Territory of the Afars and Issas
- * "Agencia Federal de Investigaciónes"
- AFIS
- * Automated Fingerprint Identification System
- * American Forces Information Service
- AFIST – Abrams Full Crew Interactive Skills Trainer
- AFJ – April Fool's Joke
- AFK – Away From Keyboard
- AFL
- * American Federation of Labor
- * American Football League — either the 1960s league that merged into the National Football League, or one of several other leagues of American football
- * Arena Football League
- * Australian Football League
- AFL–CIO –
- AFLAC – American Family Life Assurance Company of Columbus
- AFM – Army Field Manual – Atomic Force Microscope – Aviation Fleet Maintenance
- AFN – Afghani
- AFO – Association of Field Ornithologists
- AFOSR – U.S. Air Force Office of Scientific Research
- AFP
- * Agence France-Presse
- * Australian Federal Police
- AFQT – Armed Forces Qualification Test
- afr – Afrikaans language
- AFRC – Air Force Reserve Command
- AFRL – Air Force Research Laboratory
- AFROTC – Air Force Reserve Officer Training Corps
- AFRRI – Armed Forces Radiobiology Research Institute
- AFRTS – Armed Forces Radio and Television Service
- AFS
- * Active Front Steering
- * Air Facility Sub-System
- * Amniotic Fluid-derived Stem cell
- AFS&A or AFSA – U.S. Air Force Studies and Analysis
- AFSC
- * U.S. Air Force Staff College
- * U.S. Air Force Systems Command
- AFSCN – U.S. Air Force Satellite Control Network
- AFSPC – Air Force Space Command
- AFT – American Farmland Trust
- AFV – armoured fighting vehicle or America's Funniest Home Videos
- AFWA
- * Air Force Weather Agency
- * Association of Fish and Wildlife Agencies
AG
- ag – Attogram
- Ag – Silver
- AG
- * air gunner
- * Aktiengesellschaft
- * Algeria
- * Antigua and Barbuda
- * Assemblies of God
- AGA
- * AB Gas-accumulator
- * Advanced Graphics Architecture
- AGARD – Advisory Group for Aerospace Research and Development
- AGARDograph – Advanced Guidance for Alliance Research and Development publication
- AGASA – Akeno Giant Air Shower Array
- AGB – Internal Nintendo initialism for Game Boy Advance
- AGC
- * Apollo Guidance Computer
- * Automatic Gain Control
- AGC – Adjutant General's Corps
- AGDC – Australian Game Developers' Conference
- AGI – Auxiliary Group Intelligence
- AGL – Above Ground Level
- AGM – Annual General Meeting
- AGN – Active Galactic Nucleus
- AGO – Angola
- AGP – Accelerated Graphics Port
- AGRICOLA – Agriculture Online Access
- AGS – Alaska Ground Station
- AGTS – Advanced Gunnery Training System
- AGU – American Geophysical Union
- AGW – Autonomous Guided Weapon
AH
- aH – Attohenry
- Ah – Ampere hour
- AH – Attack Helicopter
- AHA – American Heart Association
- AHCPR – Agency for Health Care Policy and Research
- AHEC – Australian Health Ethics Committee
- AHPCRC – Army High Performance Computing Research Center
- AHQ – Air Headquarters
- AHRQ – Agency for Healthcare Research and Quality
- AHS – American Housing Survey
AI
- AI
- * Air Interdiction
- * Amnesty International
- * Artificial Insemination
- * Artificial Intelligence
- * Anguilla
- AIA
- * Aerospace Industries Association
- * American Institute of Architects
- * Anguilla
- AIAA – American Institute of Aeronautics and Astronautics
- AIC
- * African Independent Church
- * Animal Identification Coordinator
- AICD – Australian Institute of Company Directors
- AICMFP – And I Claim My Five Pounds
- AID – U.S. Agency for International Development
- AIDS – Acquired Immune Deficiency Syndrome
- AIHW – Australian Institute of Health and Welfare
- AIM – many, including AOL Instant Messenger, Australian Institute of Management; see entry
- AIMP – Aurora Incremental Modernization Project
- AIPAC – American Israel Public Affairs Committee
- AIR – Aircraft Inventory Record
- AIRFA – American Indian Religious Freedom Act
- AIRS – Aerometric Information Retrieval System
- AIS
- * Australian Institute of Sport
- * Automatic Identification System
- AISB – Society for the Study of Artificial Intelligence and the Simulation of Behaviour
AJ
- aJ – Attojoule
- AJ – Azerbaijan
- Ajax – Asynchronous JavaScript And XML
- AJD – Astronomical Julian day
- AJP – Allied Joint Publication
- AJPW – All Japan Pro Wrestling
AK
- ak – Akan language
- aK – Attokelvin
- AK – Alaska
- aka – Akan language
- AKA
- * Also known as
- * Above knee amputation
- AKDT – Alaska Standard Daylight Saving Time
- AKST – Alaska Standard Time
- AKP – ''Adalet ve Kalkınma Partisi''
AL
- aL – Attolitre
- Al – Aluminium
- AL
- * Alabama
- * Albania
- * Anno Lucis
- ALA – Åland
- ALAP – As Long/Late As Possible
- ALARM – Air-Launched Anti-Radar Missile
- ALB – Albania
- ALCOA or Alcoa – The Aluminum Company of America, NYSE:AA
- ALD – Accounting Line Designator
- ALERT – Advanced Linked Extended Reconnaissance and Targeting – Attack and Launch Early Reporting to Theatre
- ALF
- * Africa Leadership Forum
- * Alien Life Form
- * Animal Liberation Front
- ALG – Algeria
- ALGOL – ALGOrithmic Language
- ALL – Albanian lek
- ALOA – Associated Locksmiths of America, Inc.
- ALOC
- * Air Lines Of Communication
- * Average Length of Calls
- ALP – Australian Labor Party
- ALPA – Air Line Pilots Association
- ALS – Amyotrophic Lateral Sclerosis – Automatic Landing System
- ALSHS – Abraham Low Self-Help Systems
- ALSP – Aggregate Level Simulation Protocol
- ALTA – American Land Title Association
- ALTE – Association of Language Testers in Europe
- ALTACS – Automated decision Logic Tactical Air Combat Simulation
AM
- am
- * Amharic language
- * Attometre
- Am – Americium
- AM
- * many, including amplitude modulation and ante meridiem; see entry
- * Armenia
- AM1 – Airman 1st class
- AMA
- * American Medical Association
- * Australian Medical Association
- AMAPS – Aircraft, Missile, Avionics Performance Simulation
- AMC
- * Adaptive modulation and coding
- * U.S. Air Mobility Command
- * American Motors Corporation
- * American Movie Classics
- * U.S. Army Materiel Command
- AMCB – U.S. Army/Marine Corps Board
- AMD
- * Advanced Micro Devices
- * Age-related Macular Degeneration
- * Armenian dram
- AMF – Afghan Military Force
- AMFOM – Advanced Missile Fly Out Model
- AMFR
- * Age-specific Marital Fertility Rate
- * Amplitude Modulation Following Response
- AMFRS
- * Advanced Multi-Function Radio Frequency System
- * Automatic Multisensor Feature-based Recognition System
- amh – Amharic language
- AML – Acute Myeloid Leukaemia
- AMLCD – Active Matrix Liquid Crystal Display
- AMLO
- * Andrés Manuel López Obrador
- * Anti-Money Laundering Office — separate government agencies in Taiwan and Thailand
- AMO – Atlantic Multidecadal Oscillation
- AMOLED – Active-matrix organic light-emitting diode
- AMOS
- * Advanced MOrtar System
- * Air Force Maui Optical and Supercomputing observatory
- AMP
- * Adenosine MonoPhosphate
- * Antimicrobial peptide
- * Automated Mission Planner
- * Anak ng Puta
- * Ain't My Problem
- AMRAAM – Advanced Medium-Range Air-to-Air Missile
- AMRDEC – U.S. Aviation & Missile Research, Development, & Engineering Center
- AMS
- * Agriculture Marketing Service
- * American Mathematical Society
- AMSAA – U.S. Army Materiel Systems Analysis Activity
- AMSB – Aix Maurienne Savoie Basket
- AMSO – U.S. Army Model and Simulation Office
- AMSU – Advanced Microwave Sounding Unit
- AMTE – UK Admiralty Marine Technology Establishment
AN
- an – Aragonese language
- aN – Attonewton
- AN
- * Andorra
- * Netherlands Antilles
- ANA
- * Administration for Native Americans
- * Afghan National Army
- * All Nippon Airways
- * Anti-Nuclear Anti-body
- * Australian National Airways
- * Australian Natives' Association
- ANC – African National Congress
- AND – Andorra
- ANFO – Ammonium nitrate/fuel oil
- ANG
- * Air National Guard
- * Angola
- * Netherlands Antillian guilder
- ANGLiCo – Air/Naval Gunfire Liaison Company
- ANL – Argonne National Laboratory
- ANM – Acoustic Noise Monitor
- ANOVA – ANalysis Of VAriance
- ANS – Applied and Natural Sciences
- ANSI – American National Standards Institute
- ANTM – America's Next Top Model
- ANT
- * Netherlands Antilles
- * Antigua and Barbuda
- ANTY – Acronyms, No Thank You
- ANWA – Augusta National Women's Amateur, a prominent American golf tournament
- ANWR – Arctic National Wildlife Refuge
- ANZ – Australia and New Zealand Banking Group
- ANZAC – Australian and New Zealand Army Corps
AO
- AO
- * Angola
- * Approach Officer
- * Area of Operations
- AOA
- * Air Officer in charge of Administration
- * Argonne National Laboratory
- * Angolan kwanza
- * Award of Arms
- * Angle of Attack
- AOC
- * Air Operations Centre
- * Air Officer Commanding
- * Alexandria Ocasio-Cortez
- AOC in C – Air Officer Commanding in Chief
- AOD – Adrenalin O.D.
- AOE – Area of Effect
- AOI
- * Angle of Incidence
- * Arab Organization for Industrialization
- AOL – America OnLine
- AOR – Area of Responsibility
- AOSTH – Adventures of Sonic the Hedgehog
- AOTS – Attack of the Show!
- AOU – American Ornithologists' Union
AP
- AP
- * Advanced Placement
- * Air Publication
- * Andhra Pradesh
- * Armed Forces Pacific
- * Associated Press
- * Auto Pilot
- APA
- * Acolytes Protection Agency
- * American Psychiatric Association
- * American Psychological Association
- APB – All Points Bulletin
- APC
- * Armoured Personnel Carrier
- * Armour Piercing Capped
- APEC – Asia Pacific Economic Cooperation
- APCNR – Armour-Piercing, Composite Non-Rigid
- APCR – Armour-Piercing, Composite Rigid
- APDS – Armour-Piercing, Discarding-Sabot
- APEDS – AMSAA Performance Estimates Data System
- APEX – Applied Physics Express
- APFSDS – Armour-Piercing, Fin-Stabilised, Discarding Sabot
- APHA – American Public Health Association
- APHE – Armour-Piercing, High Explosive
- APHIS – Animal and Plant Health Inspection Service
- API – Application Programming Interface
- APL
- * A Programming Language
- * Acute Promyeloid Leukaemia
- * Anti-Personnel Landmine
- * Applied Physics Laboratory
- APM – Advanced Power Management
- APNP – Advanced Practice Nurse Prescriber
- APOD – Aerial Port Of Debarkation
- APOE – Aerial Port Of Embarkation
- APOLLO – Apache Point Observatory Lunar Laser-ranging Operation
- APP – Allied Procedural Publication
- APR – Annual Percentage Rate
- APS
- * Advanced Photo System
- * American Physical Society
- * Antiphospholipid Antibody Syndrome
AQ
- AQ
- * AdventureQuest
- * American Samoa
- * Antarctica
- * Automatic qualifier, a term used by U.S. sports media from 1998 to 2013 to refer to the six conferences whose champions automatically entered the now-defunct Bowl Championship Series of college football
- AQIM – Al-Qaeda in the Islamic Maghreb
- AQPS – Autre que pur-sang, designation of a type of French racehorse
AR
- ar – Arabic language
- Ar – Argon
- AR
- * Argentina
- * Arkansas
- * ArmaLite Rifle
- * Armour
- * Arunachal Pradesh
- ara – Arabic language
- ARAG – Advanced Research and Assessment Group
- ARB – Administrative Review Board
- ARBA – Army Review Boards Agency
- ARC
- * Appalachian Regional Commission
- * Arc-second Raster Chart
- * Association of Retarded Citizens, the original name of the organization now known as Arc of the United States
- * Athletics–Recreation Center, an indoor arena at Valparaiso University
- ARCA – Automobile Racing Club of America
- ARCENT – United States Army Central Command
- ARDA – Advanced Research and Development Activity
- ARE
- * UK Admiralty Research Establishment
- * United Arab Emirates
- ARF – ASEAN Regional Forum
- arg – Aragonese language
- ARG – Argentina
- ARH – Armed Reconnaissance Helicopter
- ARI
- * Acute Respiratory Infection
- * U.S. Army Research Institute for the Behavioral and Social Sciences
- ARL
- * UK Admiralty Research Laboratory
- * U.S. Army Research Laboratory
- * UIUC Aviation Research Laboratory
- ARM
- * Acorn RISC Machine, later Advanced RISC Machine
- * Anti-Radiation Missile
- * Adjustable-rate mortgage
- * Armenia
- ARNet – Acquisition Reform Network
- AROTS – Australian Rare Or Threatened Species
- ARP – Address Resolution Protocol – Applied Research Programme
- ARPA – Advanced Research Projects Agency
- ARRC – ACE Rapid Reaction Corps
- ARRF – Allied Rapid Reaction Force
- ARRL – American Radio Relay League
- ARS
- * Agricultural Research Service
- * Argentine peso
- ARSC – Arctic Region Supercomputing Center
- ARSPACE – U.S. Army Space Command
- ART
- * Adaptive Resonance Theory
- * Anti-Retroviral Therapy
- ARTCC – Air Route Traffic Control Center
- ARWG – Army Research Working Group
AS
- as
- * Adult swim
- * Assamese language
- * Attosecond
- aS – Attosiemens
- As – Arsenic
- AS
- * American Samoa
- * Australia
- * Assam / Asom
- * Advanced Subsidiary
- AS – ActionScript
- A/S – Anti-submarine
- A&S – Armament & Standardisation
- ASA
- * AcetylSalicylic Acid
- * American Standards Association
- * Army Security Agency
- * Atlantic Southeast Airlines
- * Alaska Airlines
- ASAP – As Soon As Possible
- ASARS
- * Advanced Synthetic Aperture Radar System
- * Airborne Search and Rescue System
- ASB – Associated Student Body – Alternative Service Book
- asbl – association sans but lucratif
- ASBO – Antisocial Behavior Order
- ASCAP – American Society of Composers, Authors, and Publishers
- ASCC
- * Army Service Component Commander
- * Automatic Sequence Controlled Calculator
- * Air Standardization Coordinating Committee
- ASCIET – All Services Combat Identification Evaluation Team
- ASCII – American Standard Code for Information Interchange
- ASC+T – Anti Slip Control + Traction
- ASD
- * Assistant Secretary of Defense
- * Autism spectrum disorder
- ASD –
- ASD – Assistant Secretary of Defense
- ASD – Assistant Secretary of Defense (Health Affairs)
- ASD – Assistant Secretary of Defense
- ASD – Assistant Secretary of Defense
- ASD – Assistant Secretary of Defense
- ASD – Assistant Secretary of Defense (Public Affairs)
- ASD – Assistant Secretary of Defense
- ASD – Assistant Secretary of Defense
- ASD –
- ASD – Assistant Secretary of Defense
- ASD – Assistant Secretary of Defense
- ASDIC – Allied Submarine Detection Investigation Committee
- ASEAN – Association of Southeast Asian Nations
- ASFAR – Americans for a Society Free of Age Restrictions
- ASG – Area Support Group
- ASIC – Australian Securities & Investments Commission – Aviation Security Identification Card
- ASICS – Anima sana in corpore sano
- ASIO
- * Australian Security Intelligence Organisation
- * Audio Stream Input/Output
- ASIP
- * Advanced System Improvement Program
- * Army Stationing and Installation Plan
- * Application-specific instruction set processor
- ASL
- * Above Sea Level
- * American Sign Language
- * "Age, Sex, Location?"
- asm – Assamese language
- ASM
- * Air-to-Surface Missile
- * American Samoa
- * American Society for Metals
- * American Society for Microbiology
- * Association Sportive Montferrandaise, as in ASM Clermont Auvergne
- ASMB
- * American Society for Matrix Biology
- * Adult Swim Message Board
- ASME
- * American Society of Mechanical Engineers
- * American Society of Magazine Editors
- ASMP
- * Air-Sol Moyenne Portée missile
- * Asymmetric multiprocessing
- ASMR – Autonomous Sensory Meridian Response
- ASN – Associate of Science in Nursing
- ASOC
- * Air Sovereignty Operations Centre
- * Air Support Operations Centre
- * Airport Security and Operations Centre
- * Antarctic and Southern Ocean Coalition
- * Atlanta Symphony Orchestra Chorus
- * Australian Standard Offence Classification
- ASP
- * Active Server Pages
- * American Society of Primatologists
- * Ammunition Supply Point
- * Application Service Provider
- * Astronomical Society of the Pacific
- * Association of Surfing Professionals
- ASPI – Australian Strategic Policy Institute
- ASR
- * Alkali-silica reaction
- * Anti Slip Regulation
- ASRAAM – Advanced Short-Range Air-to-Air Missile
- ASSC – Association for the Scientific Study of Consciousness
- Ass Paym – Assistant Paymaster
- AST – Atlantic Standard Time
- ASTIA – Armed Services Technical Information Agency
- ASTM – American Society for Testing and Materials
- ASTREA – Aerial Support To Regional Enforcement Agencies
- ASUN – Atlantic Sun Conference, now branded as the ASUN Conference
- ASUW – AntiSUrface Warfare
- ASVAB–Armed Services Vocational Aptitude Battery
- ASVEL – Association Sportive Villeurbanne Éveil Lyonnais
- ASW – AntiSubmarine Warfare
- ASWORG – AntiSubmarine Warfare Operations Research Group
- ASX
- * Advanced Stream Redirector
- * Australian Securities Exchange
AT
- aT – Attotesla
- At – Astatine
- AT – Anti-Tank – Ashmore and Cartier Islands – Austria – Advanced Technology
- ATA – Advanced Technology Attachment – Afghan Transitional Authority – Allen Telescope Array – Antarctica
- ATAC – Air Transportable Acoustic Communications
- ATACMS – Army TACtical Missile System
- ATAPI – Advanced Technology Attachment Packet Interface
- ATAS – Air-To-Air Stinger
- ATAT – Aiken Tactical Airsoft Team / Star Wars vehicle
- ATB
- * Active Time Battle
- * British Antarctic Territory
- ATC –
- * Air Traffic Control
- * Air Training Corps
- * U.S. Air Transport Command
- * Athletic Trainer, Certified
- ATCCIS – Army Tactical Command and Control Information System
- ATEBAWLS – Association Towards Engineers Balling at Wii Lover's Sports
- ATESS – Aerospace and Telecommunications Engineering Support Squadron
- ATF
- * French Southern Territories
- * Bureau of Alcohol, Tobacco, Firearms and Explosives
- ATG – Antigua and Barbuda
- ATGM – Anti-Tank Guided Missile
- ATGW – Anti-Tank Guided Weapon
- ATI –
- * Allied Telesyn International, Inc.
- * Array Technologies Incorporated.
- * Air Transport International - American cargo airline
- Atisbo – a Local Government Area in Nigeria named for constituent communities
- ATK – Attack
- ATL – Atlanta, Georgia, the largest city and capital of Georgia; taken from the IATA code for its airport
- ATLAS –
- * All-Terrain Lifter Army System
- * Assessment Tool for LAnd Systems
- ATM –
- * Automated Teller Machine
- * Asynchronous Transfer Mode
- * At The Moment
- ATN – Dronning Maud Land
- ATO
- * Air Tasking Order
- * Australian Taxation Office
- ATP
- * Adenosine TriPhosphate
- * Allied Tactical Publication
- * Ammunition Transfer Point
- * Association of Tennis Professionals
- ATSD – Assistant Secretary of Defense
- ATSDR – Agency for Toxic Substances and Disease Registry
- AT&T – American Telephone and Telegraph
- ATV
- * All-terrain vehicle
- * Associated Television – former UK TV company
- ATWA – Air, Trees, Water, Animals
AU
- Au – Gold
- AU –
- * African Union
- * American University
- * Astronomical Unit
- * Australia
- * Austria
- AUC –
- * Ab Urbe Condita / Anno Urbis Conditae
- * Area Under the Curve
- AUD – Australian dollar
- AUG – Armee-Universal-Gewehr
- AUS – Australia
- AUSCANNZUKUS – Australia, Canada, New Zealand, United Kingdom, United States
- Auslan – Australian Sign Language
- AUT – Austria
- AUTL – Army Universal Task List
AV
- av – Avar language
- aV – Attovolt
- Av – Aperture value
- AV
- * Anguilla
- * Audio-Visual
- * Aviation
- ava – Avar language
- AVA – American Viticultural Area
- AVB – Audio Video Bridging
- AVCATT-A – Aviation Combed Arms Tactical Trainer-Aviation
- AVDLR – Aviation Depot Level Repair
- ave – Avestan language
- AVGP – Armoured Vehicle, General Purpose
- AVI – Audio Video Interleave
- AVIM – Aviation Intermediate Maintenance
- AVLB – Armoured Vehicle Launched Body
- AVM
- * Air Vice-Marshal
- * Arteriovenous malformation
- AVO – Apprehended Violence Order
- AVP – Arubaanse Volkspartij
- AVP – Association of Volleyball Professionals
- AVRE – Armoured Vehicle Royal Engineers
- AVTB
- * Armoured Vehicle Test Bed
- * Aviation Test Bed
- AVUM – Aviation Unit Maintenance
- AVUS – Automobil-Verkehrs- und Übungsstraße
- AVVO – Acute Vaginal Venereal Outbreak
AW
- aW – Attowatt
- AW – Aruba
- AWA – American Wrestling Association
- AWACS – Airborne Warning And Control System
- AWC – Air Warfare Centre
- AWD – many, including All Wheel Drive; see entry
- AWE – Advanced Warfighting Experiment
- AWG – Aruban guilder
- AWOL – Absent Without Official Leave / Absent WithOut Leave
- AWP – Awaiting Parts
- AWSIM – Air Warfare SIMulation
- AWST – Australian Western Standard Time
- AWW – Above-Water Warfare
AX
AY
- ay – Aymara language
- AY – Antarctica
- AYBABTU – All Your Base Are Belong To Us
- aym – Aymara language
- AYU – As Yet Unknown
AZ
- az – Azerbaijani language
- AZ
- * Arizona
- * Azerbaijan
- * Alkmaar Zaanstreek
- AZAL – Azerbaijan Airlines
- aze – Azerbaijani language
- AZE – Azerbaijan
- AZN – Azerbaijani manat
- AZUR – ''Actions en zone urbaine''