List of acronyms and initialisms: A

This list contains acronyms, initialisms, and pseudo-blends that begin with the letter A.

For the purposes of this list:

• acronym = an abbreviation pronounced as a series of constituent letters, e.g., SARS = severe acute respiratory syndrome
• initialism = an abbreviation pronounced wholly or partly using the names of its constituent letters, e.g., CD = compact disc
• pseudo-blend = an abbreviation whose extra or omitted letters means that it cannot stand as a true acronym, initialism, or portmanteau (a word formed by combining two or more words).

(a) = acronym in the example: SARS – (a) Severe acute respiratory syndrome

(i) = initialism in the example: CD – (i) Compact disc

(p) = pseudo-blend in the example: UNIFEM – (p) United Nations Development Fund for Women

(s) = symbol (none of the above, representing and pronounced as something else; for example: MHz – Megahertz)

(Main list of acronyms and initialisms)

• a – (s) Atto-
• A – (s) Ampere

A0–9

• A2ATD or A²ATD – (i) Anti-Armour Advanced Technology Demonstration
• A2C2 or A²C² – (i) Army Airspace Command and Control
• A4 – many, including a European standard office paper size; see entry

AA

• aa – (s) Afar language (ISO 639-1 code)
• aA – (s) Attoampere
• AA
  • (i) achieved availability
  • Alcoholics Anonymous
  • (s) Armed Forces Americas (postal symbol)
  • Aruba (FIPS 10-4 territory code)
  • (i) assembly area
  • Automobile Association
  • avenue of approach
• AAA
  • (i) administration, authorization, and authentication
  • American Automobile Association ("Triple-A")
  • anti-aircraft artillery
  • Amateur Athletic Association (of England)
  • Asistencia Asesoría y Administración (Spanish, "Assistance, Consulting, and Administration"—Mexican professional wrestling promotion)
• AAAI – (i) American Association for Artificial Intelligence
• AAAS – (i) American Association for the Advancement of Science
• AAAV – (i) Advanced Amphibious Assault Vehicle
• AAC – (i) Army Air Corps (British Army)
• AAD
  • (i) analogue-analogue-digital (CD quality)
  • Australian Antarctic Division
• AADD – (i) All About Developmental Disabilities, a venue for Dave Blanchard to cheat on his wife.
• AADT – (i) annual average daily traffic
• AADAC – (a) Alberta Alcohol and Drug Abuse Commission
• AADC
  • (i) area air defense commander
  • (i) amino acid decarboxylase
  • (i) aromatic L-amino acid decarboxylase
  • (i) Australian Antarctic Data Centre
• AAFC
  • (i) U.S. Army Air Corps Ferrying Command (1941–1942)
  • All-America Football Conference (1946–1949)
• AAFES – (i) Army and Air Force Exchange Service
• AAI – (i) applied artificial intelligence
• AAIS – (i) advanced airborne interceptor simulator
• AAM – (i) air-to-air missile
• AAMOF – (i) as a matter of fact
• AAN – (i) American Academy of Nursing
• AANEAS – (a) Anglo-Australian Near-Earth Asteroid Survey
• AAODL – (i) Atmospheric Aerosols and Optics Data Library
• a.a.p. – (i) Associated Artists Productions (former film distributor)
• AAP
  • (i) advanced acquisition plan
  • Allied administrative publication
  • American Academy of Pediatrics
• AAPC – (i) Accounting and Auditing Policy Committee
• aar – (s) Afar language (ISO 639-2 code)
• AAR
  • (i) after-action review
  • Association of American Railroads
• AARP – (i/s) American Association of Retired Persons (now officially known only by the initials)
• AAS
  • (i) Advanced Automation System
  • American Astronomical Society ("double-A-S")
• AASPEM – (i) advanced air-to-air system performance evaluation model
• AAT – (i) Australian Antarctic Territory
• AAV – (i) Amphibious Assault Vehicle
• AAWC – (i) anti-air warfare commander

AB

• ab – (s) Abkhaz language (ISO 639-1 code)
• AB
  • (i) Able Seaman (both the rank and the occupation)
  • (s) Alberta (postal symbol)
• ABA
  • (i) Adriatic Basketball Association
  • American Bar Association
  • American Basketball Association
  • American Beverage Association
  • American Bicycle Association
  • American Birding Association
  • Australian Broadcasting Authority
• ABB – (i) ASEA Brown Boveri (Swiss-Swedish multinational company)
• ABBA – (a) Agnetha, Benny, Björn, Anni-Frid (Swedish pop group)
• ABC
  • (i) abstinence, be faithful, condoms
  • Active Body Control
  • airway, breathing, circulation (see CPR)
  • Alcoholic Beverage Commission
  • alien big cat
  • always be careful
  • American Bird Conservancy
  • American-born Chinese
  • American Broadcasting Company
  • anti-lock brake controller
  • Associated British Corporation
  • Atanasoff–Berry Computer
  • Atlantic Baptist College
  • atomic, biological, chemical (see NBC)
  • Australian Broadcasting Corporation
• ABCA
  • (i) American, British and Canadian Armies (originally)
  • Army Bureau of Current Affairs
• ABCS – (i) (U.S.) Army Battle Command System
• ABET – (a) Accreditation Board for Engineering and Technology
• ABFIST – (i) Advanced Bradley Full Crew Interactive Skills Trainer
• ABGI – (i) Addington-Barker Group International
• ABIN – (a) Agência Brasileira de Inteligência (Brazilian Intelligence Agency)
• abk – (s) Abkhaz language (ISO 639-2 code)
• ABL – (i) American Basketball League
• ABLE – (a) AirBorne Law Enforcement (police air support unit)
• ABM – (i) anti-ballistic missile – Asynchronous Balanced Mode – automated banking machine
• ABMC – (i) American Battle Monuments Commission
• ABN – (i) Australian Business Number (a number issued by the Australian government as registration of a business and used for taxation purposes)
• ABPI – (i) Association of the British Pharmaceutical Industry
• ABRSM – (a) Associated Board of the Royal Schools of Music
• ABS
  • (i) acrylonitrile butadiene styrene
  • anti-lock braking system
• ABSA – (a) Amalgamated Banks of South Africa ("ab-sa")
• ABSTRIPS – (p) abstraction-based STRIPS
• ABW – (s) Aruba (ISO 3166 trigram)

AC

• aC – (s) Attocoulomb
• Ac – (s) Actinium
• AC – (i) Adriamycin-Cyclophosphamide (chemotherapy) – Air Conditioning – Aircraftman – Alternating Current – ante Christum (Latin, "before Christ"; see BC) – ante cibum (Latin, "before meals") – (s) Antigua and Barbuda (FIPS 10-4 country code) – (i) Associazione Calcio (Italian, "football (soccer) club") – Altocumulus
• A/C – (i) Air Conditioned/Conditioning – Aircraft
• AC1 – Aircraftman 1st Class
• AC2 – Aircraftman 2nd Class
• ACA – (i) Airspace Control Authority – Airspace Co-ordination Area – A Current Affair
• ACARS – (a) Aircraft Communications Addressing and Reporting System
• ACAS – (a) Aboriginal Children's Advancement Society – Advisory, Conciliation and Arbitration Service
• ACB – (i) Asociación de Clubes de Baloncesto (Spanish for "Association of Basketball Clubs")
• ACC – (i) U.S. Air Combat Command – Air Component Commander – Altocumulus castellanus – Atlantic Coast Conference – Automatic Climate Control – Area Control Center, Alpine Club of Canada
• ACCA – (i) The Association of Chartered Certified Accountants – Automatic Cloud Cover Assessment
• ACCAC – (a) Awdurdod Cymwysterau, Cwricwlwm ac Asesu Cymru (Qualifications, Curriculum and Assessment Authority for Wales)
• ACCD – American Coalition of Citizens with Disabilities
• ACCS – (i) Air Communications and Control Squadron
• ACDA – (i) Arms Control & Disarmament Agency
• ACDC – (i) Alternating Current Direct Current – the name of an Australian rock music band – a term for a bisexual person
• A/Cdre – Air Commodore
• ACDT – (a) Apple Certified Desktop Technician – (a) Australian Central Daylight Time
• ACE – (a) Air Combat Emulator (computer game) – Allied Command Europe – Armored Combat Earthmover – Automatic Computing Engine
• ACES – (a) Auxiliary Campus Enterprises and Services of Alfred State College – Aerolíneas Centrales de Colombia
• ACF – (i) American Car and Foundry – American Culinary Federation – Administration for Children and Families
• ACHT – (i) Average Call Hold Time
• ACID – (a) Atomicity, Consistency, Isolation, and Durability (in databases)
• ACINT – (p) Acoustic Intelligence
• ACK – (p) Acknowledge (telecommunications; cf. NAK)
• ACL
  • (i) Access Control List
  • Anterior Cruciate Ligament
  • Atlantic Coast Line Railroad
• ACLJ – (i) American Center for Law and Justice
• ACLOS – (i) Automatic CLOS (missile control system)
• ACLS – (i) American Council of Learned Societies
• ACLU
  • (i) American Civil Liberties Union
  • American Communist Lawyers Union (pejorative slang for the above)
• ACM – many, including Association for Computing Machinery; see entry
• ACMC – (i) (U.S.) Assistant Commandant of the Marine Corps
• ACN – (i) Airborne Communications Node – Australian Company Number (number issued by the Australian government as registration of a limited liability company)
• ACO – (i) Airspace Control Order
• ACOBA – (a) Advisory Committee on Business Appointments
• ACOG – (a) American College of Obstetricians and Gynecologists
• ACOM – (p) (U.S.) Atlantic Command
• ACORN – (a) Association of Community Organizations for Reform Now
• ACP – (i) Air Control Point – African, Caribbean and Pacific Group of States
• ACR – (i) Advanced Concepts and Requirements
• ACRI – (p) African Crisis Initiative
• ACRT – (i) Advanced Concepts Research Tool simulator
• ACS – (i) Affiliated Computer Services (NYSE ACS) – American Cancer Society – American Chemical Society – Association of Caribbean States – Australian Computer Society – Alaska Communications Service
• ACSC – (i) Army Command and Staff College (various nations)
• ACST – (i) Australian Central Standard Time
• ACST – (i) American Cooperative School of Tunis
• ACT – (i) Adaptive Control of Thought (cognitive model) – Australian Capital Territory – American College Test (ing Program)
• ACTD – (i) Advanced Concept Technology Demonstration
• ACTF – (i) Australian Children's Television Foundation – (U.S.) Army Constructive Training Federation
• ACT-R – (i) ACT-Rational (cognitive model)
• ACT-R/PM – (i) ACT-R/Perceptual-Motor (cognitive model)
• ACTU – (i) Australian Council of Trade Unions
• ACU – (a) American Conservative Union
• ACUF – (i) BGN Advisory Committee on Undersea Features – (a) American Conservative Union Foundation
• ACV – (i) Armoured Combat Vehicle

AD

• AD – (i) Air Defence – (s) Andorra (ISO 3166 digram) – (i) Anno Domini (Latin, "In the year of our Lord")
• A/D – (i) Analog/Digital
• ADA – (i) Air Defence Artillery – American Dental Association – Assistant District Attorney – Americans with Disabilities Act (see also the similar but non-acronymic Ada programming language)
• ADAC – (a/i) Allgemeiner Deutscher Automobil-Club (German, "General German Automobile Club")
• ADAGE – (a) Air Defense Air to Ground Engagement (simulation)
• ADAP – (i) AIDS Drug Assistance Program
• ADAS – (a/i) Asiago-DLR Asteroid Survey
• ADAT – (i) Alesis Digital Audio Tape (recording format)
• ADatP – (p) Automated Data Processing
• ADATS – (i) Agricultural Development and Training Society – Air Defence Anti-Tank System – Australian Defence Air Traffic System
• ADB – (i) Asian Development Bank
• ADC – (i) Aide De Camp – U.S. Air Defense Command (1946–1992) – Apple Display Connector – Program Against Digital Counterfeiting of Currency
• ADCTS – (i) Advanced Distributed Combat Training System
• ADD – (i) Analog Digital Digital (CD quality) – Attention-Deficit Disorder – Administration on Developmental Disabilities
• ADDIE – (i) Analyze Design Develop Implement and Evaluate
• ADDNS – (i) Advanced Deployable Day/Night Simulation
• ADF – (i) Australian Defence Force – African Development Foundation
• ADGB – Air Defence of Great Britain
• ADHD – (i) Attention-Deficit Hyperactivity Disorder
• ADHS – (i) Attention-Deficit Hyperactivity Syndrome
• ADI – (i) Acceptable/Allowable Daily Intake
• ADIZ – (a/i) Air Defence Identification Zone
• ADL – (i) Anti-Defamation League
• ad loc. – (p) ad locum (Latin, "to/at the place")
• ADM – (i) Administrative – (s) – Admiral, and the U.S. Public Health Service Commissioned Corps – Archer Daniels Midland – Assistant Deputy Minister
• ADOA – (a/i) Air Defence Operations Area
• ADP – (i) Adenosine DiPhosphate – Army Doctrine Publication (UK, Canada, Australia) – Automatic/Automated Data Processing
• ADRG – (p) Arc-second Raster Chart (ARC) Digitized Raster Graphics
• ADS – (a/i) Active Denial System – Astrophysics Data System – Attention Deficit Syndrome
• ADSR – (i) Attack, Decay, Sustain, Release (sound envelope specification)
• ADT – (i) Atlantic Daylight Time (UTC-3 hours)
• ADTB – (i) Army Doctrine and Training Bulletin
• adv. – (p) adversus (Latin, "against")
• ADW – (i) Air Defence Warning

AE

• ae – (s) Avestan language (ISO 639-1 code)
• AE
  • (s) Armed Forces Africa/Canada/Europe/Middle East (postal symbol)
  • United Arab Emirates (ISO 3166 digram; FIPS 10-4 country code)
  • (i) Artix Entertainment
• A&E – (a/i) Arts & Entertainment Network, the original name for the U.S. TV channel now known as A&E Network
• AED – (s) United Arab Emirates dirham (ISO 4217 currency code)
• AEDT – (a) Australian Eastern Daylight Time
• AEF – (i) American Expeditionary Force
• AEGIS – (p) Airborne Early warning Ground environment Interface Segment (fake etymology)
• AEI-T – (i) Army Enterprise Infostructure-Transport
• aeq. – (p) aequalis (Latin, "equal")
• AESR – (i) Aeronautical Equipment Service Record
• AEST – (a) Australian Eastern Standard Time
• aet. – (p) aetatis (Latin, "of age", "aged")
• aet – (i) After extra time (Football)
• AEW – (i) Airborne Early Warning – Airborne Electronic Warfare

AF

• af – (s) Afrikaans language (ISO 639-1 code)
• aF – (s) Attofarad
• AF
  • (s) Afghanistan (FIPS 10-4 country code; ISO 3166 digram)
  • (i) Air Force
• AFA
  • (i) U.S. Air Force Academy
  • Asociación del Fútbol Argentino (Spanish, "Argentine Football Association")
• AFAIC – (i) As Far As I'm Concerned
• AFAICT – (i) As Far As I Can Tell
• AFAIK – (i) As Far As I Know
• AFAIR – (i) As Far As I Remember/Recall
• AFATDS – (i) Advanced Field Artillery Tactical Data System
• AFC
  • (i) American Football Conference
  • Asian Football Confederation
• AFCEA – (i) Armed Forces Communications and Electronics Association
• AFDB – (i) African Development Bank
• AFES – (i) Automatic Fire Extinguishing System
• AFG – (s) Afghanistan (ISO 3166 trigram)
• AFI
  • (s) French Territory of the Afars and Issas (ISO 3166 trigram; obsolete since 1977)
  • (i) "Agencia Federal de Investigaciónes" (México)
• AFIS
  • (a) Automated Fingerprint Identification System
  • American Forces Information Service
• AFIST – (i) Abrams Full Crew Interactive Skills Trainer
• AFJ – (i) April Fool's Joke
• AFK – (i) Away From Keyboard (Internet chat abbreviation)
• AFL
  • (i) 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 – (i) American Federation of Labor – Congress of Industrial Organizations
• AFLAC – (a) American Family Life Assurance Company of Columbus
• AFM – (i) Army Field Manual (UK; the U.S. more frequently uses just FM) – Atomic Force Microscope – Aviation Fleet Maintenance
• AFN – (s) Afghani (ISO 4217 currency code)
• AFO – (i) Association of Field Ornithologists
• AFOSR – (i) U.S. Air Force Office of Scientific Research
• AFP – (a) Australian Federal Police
• AFQT – (i) Armed Forces Qualification Test
• afr – (s) Afrikaans language (ISO 639-2 code)
• AFRC – (i) Air Force Reserve Command
• AFRL – (i) Air Force Research Laboratory
• AFROTC – (i) Air Force Reserve Officer Training Corps
• AFRRI – (i, U.S.) Armed Forces Radiobiology Research Institute
• AFRTS – (i) Armed Forces Radio and Television Service
• AFS
  • (i) Active Front Steering
  • Air Facility Sub-System
  • Amniotic Fluid-derived Stem cell
• AFS&A or AFSA – (i) U.S. Air Force Studies and Analysis
• AFSC
  • (i) U.S. Air Force Staff College (obsolete; replaced with JFSC)
  • U.S. Air Force Systems Command
• AFSCN – (i) U.S. Air Force Satellite Control Network
• AFSPC – (i) Air Force Space Command
• AFT – American Farmland Trust
• AFV – (i) Armoured Fighting Vehicle
• AFWA
  • (a) Air Force Weather Agency
  • Association of Fish and Wildlife Agencies

AG

• ag – (s) Attogram
• Ag – (s) Silver (Latin argentum)
• AG – (i) air gunner – Aktiengesellschaft (German, "incorporated") – (s) Algeria (FIPS 10-4 country code) – Antigua and Barbuda (ISO 3166 digram) – Assemblies of God
• AGA – (a/i) AB Gas-accumulator ("ah-gah", Swedish company) – Advanced Graphics Architecture
• AGARD – (a) Advisory Group for Aerospace Research and Development
• AGARDograph – (p) Advanced Guidance for Alliance Research and Development publication
• AGASA – (a) Akeno Giant Air Shower Array (cosmic ray detector)
• AGB – (i) Internal Nintendo initialism (Advanced Game Boy) for Game Boy Advance
• AGC – (i) Apollo Guidance Computer – Automatic Gain Control
• AGC – (i) Adjutant General's Corps (British Army)
• AGDC – (i) Australian Game Developers' Conference
• AGI – (i) Auxiliary Group Intelligence
• AGL – (i) Above Ground Level
• AGM – (i) Annual General Meeting
• AGN – (i) Active Galactic Nucleus
• AGO – (s) Angola (ISO 3166 trigram)
• AGP – (i) Accelerated Graphics Port
• AGRICOLA (a) Agriculture Online Access
• AGS – (i) Alaska Ground Station (LandSat)
• AGTS – (i) Advanced Gunnery Training System
• AGU – (i) American Geophysical Union
• AGW – (i) Autonomous Guided Weapon

AH

• aH – (s) Attohenry
• Ah – (s) Ampere-hour
• AH – (i) Attack Helicopter
• AHA – (i) American Heart Association
• AHCPR – (i) Agency for Health Care Policy and Research (obsolete; replaced with AHRQ)
• AHEC – (i) Australian Health Ethics Committee
• AHPCRC – (i) Army High Performance Computing Research Center
• AHQ – Air Headquarters
• AHRQ – (i) Agency for Healthcare Research and Quality
• AHS – (i) American Housing Survey

AI

• AI
  • (i) Air Interdiction
  • Amnesty International
  • Artificial Insemination
  • Artificial Intelligence
  • (s) Anguilla (ISO 3166 digram)
• AIA
  • (i) Aerospace Industries Association
  • American Institute of Architects
  • (s) Anguilla (ISO 3166 trigram)
• AIAA – (i) American Institute of Aeronautics and Astronautics
• AIC
  • (i) African Independent Church
  • Animal Identification Coordinator
• AICD – (i) Australian Institute of Company Directors
• AICMFP – (i) And I Claim My Five Pounds
• AID – (i) U.S. Agency for International Development
• AIDS – (a) Acquired Immune Deficiency Syndrome
• AIM – many, including AOL Instant Messenger, Australian Institute of Management; see entry
• AIMP – (i) Aurora Incremental Modernization Project
• AIPAC – (i) American Israel Public Affairs Committee
• AIR – (i) Aircraft Inventory Record
• AIRFA – (a) American Indian Religious Freedom Act
• AIRS – (a/i) Aerometric Information Retrieval System (obsolete; replaced with AFS)
• AIS
  • (i) Australian Institute of Sport
  • Automatic Identification System
• AISB – (i) (British Society for the Study of) Artificial Intelligence and the Simulation of Behaviour

AJ

• aJ – (s) Attojoule
• AJ – (s) Azerbaijan (FIPS 10-4 country code)
• Ajax – (a) Asynchronous JavaScript And XML
• AJD – (i) Astronomical Julian Day
• AJP – (i) Allied Joint Publication
• AJPW – (i) All Japan Pro Wrestling

AK

• ak – (s) Akan languages (ISO 639-1 code)
• aK – (s) Attokelvin
• AK – (s) Alaska (postal symbol)
• aka – (s) Akan languages (ISO 639-2 code)
• a.k.a. – (i) Also known as (i.e.: alias)
• AKDT – (p) Alaska Standard Daylight Saving Time (UTC-8 hours)
• AKST – (p) Alaska Standard Time (UTC-9 hours)
• AKA – Above knee amputation (orthopaedic usage)

AL

• aL – (s) Attolitre
• Al – (s) Aluminium
• AL
  • (s) Alabama (postal symbol)
  • Albania (FIPS 10-4 country code; ISO 3166 digram)
  • (i) Anno Lucis (Latin, "Year of Light", in Masonic tradition, most often seen on plaques bearing the founding dates of buildings, in years AD and years AL)
• ALA – (s) Åland Islands (ISO 3166 trigram)
• ALAP – (a) As Long/Late As Possible
• ALARM – (a) Air-Launched Anti-Radar Missile
• ALB – (s) Albania (ISO 3166 trigram)
• ALD – (i) Accounting Line Designator (nuclear weapon targeting)
• ALERT – (a) Advanced Linked Extended Reconnaissance and Targeting – Attack and Launch Early Reporting to Theatre
• ALF
  • (a) Africa Leadership Forum
  • Alien Life Form (cf. ALF (TV series))
  • Animal Liberation Front
• ALG – (s) Algeria (IOC and FIFA trigram, but not ISO 3166)
• ALGOL – (p) ALGOrithmic Language
• ALL – (s) Albanian lek (ISO 4217 currency code)
• ALOA – (i) Associated Locksmiths of America, Inc.
• ALOC – (a) Air Lines Of Communication
• ALOC – (a) Average Length of Calls
• ALPA – (a) Air Line Pilots Association
• ALS – (i) Amyotrophic Lateral Sclerosis – Automatic Landing System
• ALSHS – (a) Abraham Low Self-Help Systems
• ALSP – (i) Aggregate Level Simulation Protocol
• ALTE – (a) Association of Language Testers in Europe
• ALTACS – (p) Automated decision Logic Tactical Air Combat Simulation

AM

• am – (s) Amharic language (ISO 639-1 code) – Attometre
• Am – (s) Americium
• AM – many, including Amplitude Modulation and Ante Meridiem; see entry – (s) Armenia (FIPS 10-4 country code; ISO 3166 digram)
• AM1 – Airman 1st class
• AMA – (i) American Medical Association – (i) Australian Medical Association
• AMAPS – (a) Aircraft, Missile, Avionics Performance Simulation
• AMC – (i) Adaptive modulation and coding (digital communications) – U.S. Air Mobility Command – American Motors Corporation – U.S. Army Materiel Command – American Movie Classics (TV network; now known simply by the initials)
• AMCB – (i) U.S. Army/Marine Corps Board
• AMD – (i) Advanced Micro Devices – Age-related Macular Degeneration – (s) Armenian dram (ISO 4217 currency code)
• AMF – (i) Afghan Military Force(s)
• AMFOM – (i) Advanced Missile Fly Out Model ("am-fomm")
• AMFR – (i) Age-specific Marital Fertility Rate – Amplitude Modulation Following Response
• AMFRS – (i) Advanced Multi-Function Radio Frequency System – Automatic Multisensor Feature-based Recognition System
• amh – (s) Amharic language (ISO 639-2 code)
• AML – (i) Acute Myeloid Leukaemia
• AMLCD – (i) Active Matrix Liquid Crystal Display
• AMO – (i) Atlantic Multidecadal Oscillation
• AMOLED – (i) Active-matrix organic light-emitting diode
• AMOS – (a) Advanced MOrtar System – Air Force Maui Optical and Supercomputing observatory
• AMP – (i) Adenosine MonoPhosphate – Automated Mission Planner
• AMRAAM – (a) Advanced Medium-Range Air-to-Air Missile
• AMRDEC – (i) U.S. Aviation & Missile Research, Development, & Engineering Center
• AMS – (i) Agriculture Marketing Service – American Mathematical Society
• AMSAA – (i/a) U.S. Army Materiel Systems Analysis Activity
• AMSO – (i/a) U.S. Army Model and Simulation Office
• AMSU – (i) Association for Managers in Students' Unions – Aviation Matériel Screening Unit
• AMTE – (i) UK Admiralty Marine Technology Establishment (1977–1984)

AN

• an – (s) Aragonese language (ISO 639-1 code)
• aN – (s) Attonewton
• AN
  • (s) Andorra (FIPS 10-4 country code)
  • Netherlands Antilles (ISO 3166 digram)
• ANA
  • (i) Administration for Native Americans
  • Afghan National Army
  • All Nippon Airways
  • Anti-Nuclear Anti-body
  • (a) Australian National Airways
  • Australian Natives Association
• ANC – (i) African National Congress
• AND – (s) Andorra (ISO 3166 trigram)
• ANFO – (i) Ammonium nitrate/fuel oil (explosive)
• ANG
  • (i) Air National Guard
  • (s) Angola (IOC and FIFA trigram, but not ISO 3166)
  • (s) Netherlands Antillian guilder (ISO 4217 currency code)
• ANGLiCo – (p) Air/Naval Gunfire Liaison Company
• ANL – (i) Argonne National Laboratory
• ANM – (i) Acoustic Noise Monitor
• ANOVA – (p) ANalysis Of VAriance
• ANS – (i) Applied and Natural Sciences
• ANSI – (a) American National Standards Institute
• ANTM – (i) America's Next Top Model
• ANT
  • (s) Netherlands Antilles (ISO 3166 trigram)
  • Antigua and Barbuda (IOC trigram, but not ISO 3166 or FIFA)
• ANWR – (i) Arctic National Wildlife Refuge (often pronounced /ˈænwɑr/ as if it were an acronym)
• ANZ – (s) Australia and New Zealand Banking Group
• ANZAC – (a) Australian and New Zealand Army Corps

AO

• AO – (s) Angola (FIPS 10-4 country code; ISO 3166 digram) – (i) Approach Officer (submarine) – Area of Operations
• AOA – (i) Air Officer in charge of Administration – Argonne National Laboratory – (s) Angolan kwanza (ISO 4217 currency code) – (i) Award Of Arms (heraldry)
• AOC – (i) Air Operations Centre – Air Officer Commanding
• AOC in C – Air Officer Commanding in Chief
• AOD – (i) Adrenalin O.D. (punk rock band)
• AOI – (i) Angle Of Incidence (i) Arab Organization for Industrialization
• AOL – (i) America OnLine
• AOR – (i) Area of Responsibility
• AOSTH – Adventures of Sonic the Hedgehog
• AOU – (i) American Ornithologists' Union

AP

• AP – (i) Advanced Placement – Air Publication – (s) Armed Forces Pacific (postal symbol) – (i) Associated Press – Auto Pilot
• APA –(i) American Psychiatric Association
• APB – (i) All Points Bulletin (police jargon)
• APC – (i) Armoured Personnel Carrier – Armour Piercing Capped (ammunition)
• APEC – (a) Asia Pacific Economic Cooperation
• APCNR – (i) Armour-Piercing, Composite Non-Rigid (ammunition)
• APCR – (i) Armour-Piercing, Composite Rigid (ammunition)
• APDS – (i) Armour-Piercing, Discarding-Sabot (ammunition)
• APEDS – (a) AMSAA Performance Estimates Data System
• APEX – (p) Applied Physics Express
• APFSDS – (i) Armour-Piercing, Fin-Stabilised, Discarding Sabot (ammunition)
• APHA – (i) American Public Health Association
• APHE – (i) Armour-Piercing, High Explosive (ammunition)
• APHIS – (a) Animal and Plant Health Inspection Service
• API – (i) Application Programming Interface
• APL – (i) A Programming Language – Acute Promyeloid Leukaemia – Anti-Personnel Landmine – Applied Physics Laboratory (Johns Hopkins University)
• APM – (i) Advanced Power Management
• APOD – (i) Aerial Port (Airport) Of Debarkation
• APOE – (i) Aerial Port (Airport) Of Embarkation
• APOLLO – (a) Apache Point Observatory Lunar Laser-ranging Operation
• APP – (i) Allied Procedural Publication
• APR – (i) Annual Percentage Rate
• APS – (i) American Physical Society – Antiphospholipid Antibody Syndrome

AQ

• AQ
  • (i) AdventureQuest
  • (s) American Samoa (FIPS 10-4 territory code)
  • Antarctica (ISO 3166 digram)
  • (i) Automatic qualifier, a term used by U.S. sports media to refer to the six conferences whose champions automatically enter the Bowl Championship Series of college football

AR

• ar – (s) Arabic language (ISO 639-1 code)
• Ar – (s) Argon
• AR – (s) Argentina (FIPS 10-4 country code; ISO 3166 digram) – Arkansas (postal symbol) – Armour
• ara – (s) Arabic language (ISO 639-2 code)
• ARAG – (a) Advanced Research and Assessment Group
• ARB – (i) Administrative Review Board
• ARBA – (a/i) Army Review Boards Agency
• ARC – (i) Arc-second Raster Chart – Appalachian Regional Commission
• ARCA – (a) Automobile Racing Club of America
• ARCENT – (p) United States Army Central Command
• ARDA – (a) Advanced Research and Development Activity (became DTO 2006)
• ARE – (i) UK Admiralty Research Establishment (–1991) – (s) United Arab Emirates (ISO 3166 trigram)
• ARF – (i) ASEAN Regional Forum
• arg – (s) Aragonese language (ISO 639-2 code)
• ARG – (s) Argentina (ISO 3166 trigram)
• ARH – (s) Armed Reconnaissance Helicopter
• ARI – (i) Acute Respiratory Infection – U.S. Army Research Institute for the Behavioral and Social Sciences
• ARL – (i) UK Admiralty Research Laboratory (1921–1977) – U.S. Army Research Laboratory – UIUC Aviation Research Laboratory
• ARM – (a) Anti-Radiation Missile – Adjustable Rate Mortgage – (s) Armenia (ISO 3166 trigram)
• ARNet – (p) Acquisition Reform Network
• ARP – (i) Address Resolution Protocol – Applied Research Programme
• ARPA – (a) Advanced Research Projects Agency
• ARRC – (i) ACE Rapid Reaction Corps
• ARRF – (i) Allied Rapid Reaction Force
• ARRL -
• ARS – (i) Agricultural Research Service – (s) Argentine peso (ISO 4217 currency code)
• ARSC – (i) Arctic Region Supercomputing Center
• ARSPACE – (p) U.S. Army Space Command
• ART – (a) Adaptive Resonance Theory – Anti-Retroviral Therapy
• ARTCC – (i) Air Route Traffic Control Center
• ARWG – (i) Army Research Working Group ("are-wig")

AS

• as – (i) Adult swim – (s) Assamese language (ISO 639-1 code) – Attosecond
• aS – (s) Attosiemens
• As – (s) Arsenic
• AS – (s) American Samoa (postal symbol; ISO 3166 digram) – Australia (FIPS 10-4 country code)
• AS – (i) ActionScript
• A/S – (i) Anti-submarine
• A&S – (i) Armament & Standardisation
• ASA – (i) AcetylSalicylic Acid – American Standards Association – Army Security Agency – Atlantic Southeast Airlines
• ASAP – (a) As Soon As Possible
• ASARS – (a) Advanced Synthetic Aperture Radar System – Airborne Search and Rescue System
• ASB – (i) Associated Student Body – Alternative Service Book (Church of England)
• asbl – (i) association sans but lucratif (French "Non-profit organisation")
• ASBO – (a) Anti-Social Behaviour Order
• ASCAP – (a) American Society of Composers, Authors, and Publishers
• ASCC – (i) Army Service Component Commander – Automatic Sequence Controlled Calculator – Air Standardization Coordinating Committee
• ASCIET – (i) All Services Combat Identification Evaluation Team
• ASCII – (a) American Standard Code for Information Interchange
• ASC+T – (i) Anti Slip Control + Traction
• ASD – (i) (U.S.) Assistant Secretary of Defense – autism spectrum disorder
• ASD(C3I) – (i) (U.S.) (Command, Control, Communications, & Intelligence)
• ASD(FMP) – (i) (U.S.) Assistant Secretary of Defense (Force Management Policy)
• ASD(HA) – (i) (U.S.) Assistant Secretary of Defense (Health Affairs)
• ASD(ISA) – (i) (U.S.) Assistant Secretary of Defense (International Security Affairs)
• ASD(ISP) – (i) (U.S.) Assistant Secretary of Defense (International Security Policy)
• ASD(LA) – (i) (U.S.) Assistant Secretary of Defense (Legislative Affairs)
• ASD(PA) – (i) (U.S.) Assistant Secretary of Defense (Public Affairs)
• ASD(RA) – (i) (U.S.) Assistant Secretary of Defense (Reserve Affairs)
• ASD(SO&HA) – (i) (U.S.) Assistant Secretary of Defense (Special Operations & Humanitarian Assistance)
• ASD(SO/LIC) – (i) (U.S.) (Special Operations & Low-Intensity Conflict)
• ASD(S&R) – (i) (U.S.) Assistant Secretary of Defense (Strategy & Requirements)
• ASD(S&TR) – (i) (U.S.) Assistant Secretary of Defense (Strategy & Threat Reduction)
• ASDIC – (a) Allied Submarine Detection Investigation Committee (Sonar)
• ASEAN – (a) Association of South East Asian Nations
• ASFAR – (a) Americans for a Society Free of Age Restrictions
• ASG – (i) Area Support Group
• ASIC – (a) Australian Securities and Investments Commission – (a) Aviation Security Identification Card
• ASICS – (a) Anima sana in corpore sano (Latin, "A sound mind in a sound body") (athletic shoe manufacturer)
• ASIO – (a) Australian Security Intelligence Organisation – (a) Audio stream input output
• ASIP – (i) Advanced System Improvement Program – Army Stationing and Installation Plan – Application-specific instruction-set processor
• ASL – (i) Above Sea Level – American Sign Language (also known as Ameslan) – "Age, Sex, Location?" (Internet slang)
• asm – (s) Assamese language (ISO 639-2 code)
• ASM – (i) Air-to-Surface Missile – (s) American Samoa (ISO 3166 trigram) – (i) American Society for Metals – (i) American Society for Microbiology
• ASMB – (i) American Society for Matrix Biology – Adult Swim Message Board
• ASME – (i) American Society of Mechanical Engineers – American Society of Magazine Editors
• ASMP – (i) Air-Sol Moyenne Portée missile (French "Medium-range air to surface") – (p) Asymmetric multiprocessing
• ASN – (i) Associate of Science in Nursing
• ASOC – (a/i) 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 – (i) Active Server Pages – American Society of Primatologists – Ammunition Supply Point – Application Service Provider (cf internet service provider) – Astronomical Society of the Pacific – Association of Surfing Professionals
• ASPI – (i) Australian Strategic Policy Institute
• ASR – (i) Alkali-silica reaction – Anti Slip Regulation
• ASRAAM – (a) Advanced Short-Range Air-to-Air Missile
• ASSC – (i) Association for the Scientific Study of Consciousness
• Ass Paym – Assistant Paymaster
• AST – (i) Atlantic Standard Time (UTC-4 hours)
• ASTIA – (a) Armed Services Technical Information Agency
• ASTM – (i) American Society for Testing and Materials
• ASTREA – (a) Aerial Support To Regional Enforcement Agencies (sheriff's air support unit)
• ASUW – (p) AntiSUrface Warfare
• ASVAB - Armed Services Vocational Aptitude Battery(taken by juniors in high school in the USA)
• ASVEL – (a) Association Sportive Villeurbanne Éveil Lyonnais (Association Sportive is French for "Sporting Association"; the club was founded through the merger of AS Villeurbanne and Éveil Lyonnais)
• ASW – (i) AntiSubmarine Warfare
• ASWORG – (i) (U.S.) AntiSubmarine Warfare Operations Research Group
• ASX – (p) Advanced Stream Redirector – Australian Securities Exchange

AT

• aT – (s) Attotesla
• At – (s) Astatine
• AT – (i) Anti-Tank – (s) Ashmore and Cartier Islands (FIPS 10-4 territory code) – Austria (ISO 3166 digram) – (i) Advanced Technology (IBM Personal Computer/AT)
• ATA – (i) Advanced Technology Attachment (IBM Personal Computer) – Afghan Transitional Authority – Allen Telescope Array – (s) Antarctica (ISO 3166 trigram)
• ATAC – (a) Air Transportable Acoustic Communications
• ATACMS – (p) Army TACtical Missile System
• ATAPI – (a) Advanced Technology Attachment Packet Interface
• ATAS – (a) Air-To-Air Stinger (missile)
• ATAT – (a) Aiken Tactical Airsoft Team / Star Wars vehicle
• ATB – (i) Active Time Battle – (s) British Antarctic Territory (ISO 3166 trigram; merged with AQ in 1979)
• ATC – (i) Air Traffic Control – Air Training Corps – U.S. Air Transport Command (1942–1948)- Athletic Trainer, Certified (www.nata.org)
• ATCCIS – (i) Army Tactical Command and Control Information System
• ATESS – (i) Aerospace and Telecommunications Engineering Support Squadron
• ATF – (s) French Southern Territories (ISO 3166 trigram) – (i) (U.S.) Bureau of Alcohol, Tobacco, Firearms and Explosives (from its previous name, which did not include "Explosives")
• ATG – (s) Antigua and Barbuda (ISO 3166 and FIFA trigram)
• ATGM – (i) Anti-Tank Guided Missile
• ATGW – (i) Anti-Tank Guided Weapon
• ATI – (i) Allied Telesyn International, Inc.
• Atisbo – a Local Government Area in Nigeria named for constituent communities (Ago-Are, Tede, Irawo, Sabe, Baasi, Ofiki and Owo)
• ATK – (p) Attack
• ATL – (p) Atlanta, Georgia, the largest city and capital of Georgia
• ATLAS – (a) All-Terrain Lifter Army System – (p) Assessment Tool for LAnd Systems
• ATM – (i) Automated Teller Machine – Asynchronous Transfer Mode – At The Moment
• ATN – (s) Dronning Maud Land (ISO 3166 trigram; merged with AQ in 1983)
• ATO – (i) Air Tasking Order – Australian Taxation Office
• ATP – (i) Adenosine TriPhosphate – Allied Tactical Publication – Ammunition Transfer Point
• ATSD – (p) (U.S.) Assistant to the Secretary of Defense
• ATSDR – (i) Agency for Toxic Substances and Disease Registry
• AT&T – (i) American Telephone and Telegraph (U.S. company, also known as "Ma Bell")
• ATV – (i) All-Terrain Vehicle
• ATWA – (a) Air, Trees, Water, Animals

AU

• Au – (s) Gold
• AU – (i) African Union (was OAU before 2000) – American University – (s) Astronomical Unit – Australia (ISO 3166 digram) – Austria (FIPS 10-4 country code)
• AUC – (i) Ab Urbe Condita / Anno Urbis Conditae (Latin "from the founding of the city" / "in the year since the founding of the city") (of Rome) – Area Under the Curve (concentration time curve; medicine)
• AUD – (s) Australian dollar (ISO 4217 currency code)
• AUS – (s) Australia (ISO 3166 trigram)
• AUSCANNZUKUS – (p) Australia, Canada, New Zealand, United Kingdom, United States (security designation)
• AUT – (s) Austria (ISO 3166 trigram)
• AUTL – (i) Army Universal Task List

AV

• av – (s) Avar language (ISO 639-1 code)
• aV – (s) Attovolt
• Av – (i) Aperture value (photographic mode)
• AV
  • (s) Anguilla (FIPS 10-4 territory code)
  • (i) Audio-Visual
  • (s) Aviation
• ava – (s) Avar language (ISO 639-2 code)
• AVA – (i) American Viticultural Area
• AVB – (i) Audio Video Bridging
• AVCATT-A – (p) (U.S. Army's) Aviation Combed Arms Tactical Trainer-Aviation [Reconfigurable Manned Simulator]
• AVDLR – (p) Aviation Depot Level Repair
• ave – (s) Avestan language (ISO 639-2 code)
• AVGP – (i) Armoured Vehicle, General Purpose
• AVI – (i) Audio Video Interleave
• AVIM – (p) Aviation Intermediate Maintenance
• AVLB – (i) Armoured Vehicle Launched Body
• AVM
  • (i) Air Vice-Marshal
  • (p) Arteriovenous malformation
• AVO – (i) Apprehended Violence Order
• AVP – (a) Arubaanse Volkspartij
• AVP – (i) Association of Volleyball Professionals
• AVRE – (i) Armoured Vehicle Royal Engineers
• AVTB
  • (i) Armoured Vehicle Test Bed
  • (p) Aviation Test Bed
• AVUM – (p) Aviation Unit Maintenance

AW

• aW – (s) Attowatt
• AW – (s) Aruba (ISO 3166 digram)
• AWA – (i) American Wrestling Association
• AWACS – (a) Airborne Warning And Control System
• AWC – (i) Air Warfare Centre
• AWD – many, including All Wheel Drive; see entry
• AWE – (i/a) Advanced Warfighting Experiment
• AWG – (s) Aruban guilder (ISO 4217 currency code)
• AWOL – (a) Absent Without Official Leave / Absent WithOut Leave (military jargon)
• AWP – (p) Awaiting Parts (SM&R code)
• AWSIM – (p) Air Warfare SIMulation
• AWST – (a) Australian Western Standard Time
• AWW – (i) Above Water Warfare

AX

• AX – (s) Åland Islands (ISO 3166 digram)
• AXP – (p) Ambulance eXchange Point

AY

• ay – (s) Aymara language (ISO 639-1 code)
• AY – (s) Antarctica (FIPS 10-4 territory code)
• AYBABTU – (i) All Your Base Are Belong To Us
• aym – (s) Aymara language (ISO 639-2 code)
• AYU – (i) As Yet Unknown

AZ

• az – (s) Azerbaijani language (ISO 639-1 code)
• AZ
  • (s) Arizona (postal symbol)
  • Azerbaijan (ISO 3166 digram)
  • (i) Alkmaar Zaanstreek (Dutch football club)
• aze – (s) Azerbaijani language (ISO 639-2 code)
• AZE – (s) Azerbaijan (ISO 3166 trigram)
• AZN – (s) Azerbaijani manat (ISO 4217 currency code)
• AZUR – (p) Actions en zone urbaine (French, Urban Operations)