| A | Ampère/amp |
| A/C | Aircraft |
| A/D | Analogue-to-digital |
| A/G | Air-to-ground |
| AA | Air armament |
| Air-to-air |
| Anti-aircraft |
| Apparent altitude (nav) |
| AAA | Anti-aircraft artillery |
| AAAW | Advanced air-launched anti-armour weapon |
| AAC | Army Air Corps |
| Automatic amplitude control |
| AACI | Airport Association Council International |
| AAD | Advanced ammunition depot |
| AAEE | Aeroplane and Armament Experimental Establishment |
| AAGW | Air-to-air guided weapon |
| AAIB | Air Accidents Investigation Board (UK) |
| Air Accidents Investigation Branch |
| AAL | Above aerodrome level |
| AAM | Air-to-air missile |
| AAMG | Anti-aircraft machine gun |
| AAR | Against all risks (insurance) |
| Air-to-air refuelling |
| AAS | Airport advisory service |
| AAW | Air-to-air warfare |
| AB | Air base |
| ABAC | Association of British Aviation Consultants |
| ABCC | Airborne command centre |
| ABCCC | Airborne battlefield command and control centre (USA) |
| ABLE | Automotive bridge-launching equipment |
| ABM | Anti-ballistic missile |
| ABN | Aerodrome beacon |
| ABS | Acrylonite butadiene styrene |
| Anti-lock braking system |
| AC | Advisory circular |
| Air co-ordinator |
| Atlantic Council |
| ac | Alternating current |
| ACA | Agile combat aircraft |
| Airspace control authority |
| ACARD | Advisory Council for Applied Research and Development |
| ACARS | Aircraft communication addressing and reporting system |
| ACAS | Airborne collision avoidance system |
| ACAVP | Advanced composite armoured vehicle platform |
| ACC | Air control centre |
| Area control centre |
| acc | Accumulator |
| ACCIS | Automated command, control and information system |
| ACCS | Air command and control system |
| ACCSA | Allied Communications and Computers Security Agency |
| ACD | Automatic call distribution |
| ACDA | Arms Control and Disarmament Agency (US) |
| ACE | Association of Consulting Engineers |
| Automatic calibration and equalisation (audio/radio) |
| ACED | Advanced communications equipment depot |
| acft | Aircraft |
| ACG | Amphibious combat group |
| ACI | Airports Council International |
| ACM | Air combat manoeuvre |
| ACMI | Air combat manoeuvring instrumentation |
| ACMO | Air command and control systems management organisation |
| ACMR | Air combat manoeuvring range |
| ACO | Airspace control order |
| ACOC | Air command operations centre |
| ACP | Advanced command post |
| Allied communications procedure(s) |
| ACR | Airfield control and reporting |
| Airfield control radar |
| Approach control radar |
| ACS | Automatic control system |
| ACSM | Assemblies, components, spare parts and materials |
| ACT | Active control technology |
| Air control team |
| ACV | Air control valve |
| Air cushion vehicle |
| Armoured cavalry vehicle |
| Armoured command vehicle |
| ACW | Advanced conventional weapons |
| Anti-carrier warfare |
| AD | Air defence |
| Airworthiness directive |
| Armoured division |
| ADA | Airborne data automation |
| ADAS | Air defence alerting system |
| ADATS | Air defence anti-tank system |
| ADC | Aerodrome control |
| Aide-de-camp |
| Air data computer |
| Air defence command |
| ADCC | Air defence control centre |
| ADCE | Audio distribution and control equipment |
| ADCIS | Air defence command information system |
| ADCP | Air defence command post |
| ADE | Aerial delivery equipment |
| ADELT | Automatically deployable emergency locator transmitter |
| ADEW | Air defence early warning |
| ADF | Automatic direction finder |
| Aviation digital forecast (meteorological) |
| ADGE | Air defence ground environment |
| ADH | Automated data handling |
| ADI | Attitude direction indicator |
| ADIS | Airport display information system |
| Automated data interchange system |
| ADIZ | Air defence identification zone |
| Adjt | Adjutant |
| ADL | Automatic data link |
| Automatic data logging |
| ADM | Area denial munition |
| Atomic demolition munition |
| Adm | Admiral |
| admin | Administration |
| ADML | Atomic demolition munition location |
| ADNC | Air defence notification centre |
| ADOC | Air defence operations centre |
| ADOLT | Air defence operations liaison team |
| ADP | Allied defence publication (NATO) |
| Automatic data processing |
| ADPCM | Adaptive delta pulse code modulation (radio) |
| ADPS | Automatic data processing system |
| ADR | Accident data recorder |
| Advisory route |
| Air defence radar |
| Air defence region |
| Airfield damage repair |
| ADRS | Automatic data reporting system |
| ADS | Active diffusing sonar |
| Automatic dependent surveillance |
| adsel | Address selective (radar) |
| ADSIA | Allied Data System Interoperability Agency |
| ADSU | Air data sensor unit |
| ADT | Approved departure time |
| ADU | Aircraft display unit |
| AEA | Aircraft Electronics Association (UK) |
| Association of European Airlines |
| AEEC | Aircraft Electronic and Engineering Committee |
| AEGIS | Airborne early warning ground integration segment/system |
| AEP | Allied engineering publication |
| AES | Advanced Encryption Standard |
| AESP | Army equipment support publications |
| AETP | Allied electronic publication |
| AEW | Airborne early warning |
| AEWTF | Aircrew electronic warfare tactics facility |
| AF | Air force |
| Audio frequency |
| AFB | Air force base |
| Axial folding bridge |
| AFC | Automatic fading control (radio) |
| Automatic frequency control |
| AFCS | Advanced fire control system |
| Automatic flight control system |
| AFFF | Aqueous film-forming foam (fire-fighting) |
| Automatic film-forming foam (fire-fighting) |
| AFIS | Airport flight information service |
| AFM | Adaptive frequency monitoring |
| Atomic force microscope |
| AFS | Aerodrome fire service |
| Aeronautical fixed service |
| Automatic flight system |
| AFTN | Aeronautical fixed telecommunications network |
| AFU | Assault fire unit |
| AFV | Armoured fighting vehicle |
| AG | Air-to-ground |
| Army group |
| AGA | Air-ground-air |
| AGARD | Advisory Group for Aerospace Research and Development |
| AGC | Amphibious group command |
| Automatic gain control (radio) |
| AGL | Above ground level |
| Automatic grenade launcher |
| AGM | Air-to-ground missile |
| Annual general meeting |
| AGNIS | Azimuth guided nose-in system |
| AGOS | Air-to-ground operations section |
| AGS | Aircraft general spares |
| AGZ | Actual ground zero |
| AH | Artificial horizon |
| Attack helicopter |
| ahd | Ahead |
| AHM | Anti-helicopter mine |
| AHRS | Aircraft heading reference system |
| AHS | Airborne homing system |
| AI | Air intercept(or) |
| Aircraft instruments and aircrew station |
| Artificial intelligence |
| AIAA | Area of intense aerial activity |
| AIB | Accident Information Branch (UK Department of Trade and Industry) |
| AIC | Aeronautical Information Circular |
| AICV | Armoured infantry combat vehicle |
| AID | Agency for International Development |
| AIDS | Airborne integrated data system |
| AIF | Automated intelligence file |
| AIG | Address indicator group |
| AIM | Aeronautical information manual |
| Air-intercept missile |
| AINS | Area inertial navigation system |
| AIO | Action information organisation |
| AIP | Aeronautical information publication |
| Air-independent propulsion (submarine) |
| AIR | Air intercept radar |
| Air interception radar |
| AIRAC | Aeronautical information regulation and control |
| AIRCAT | Automated integrated radar control for air traffic |
| airep | Air report |
| airmet | Air meteorological information |
| AIS | Advanced identification system |
| Aeronautical Information Service |
| Automatic identification system (for ships) |
| AJ | Anti-jamming |
| ALAE | Association of Licensed Aircraft Engineers |
| ALARP | As low as reasonably practicable |
| ALCM | Air-launched cruise missile |
| Algol | Algorithmic language (computer) |
| ALM | Air-launched missile |
| Aircraft landing mat |
| ALMV | Air-launched miniature vehicle |
| ALO | Air liaison officer |
| ALRS | Admiralty list of radio signals |
| ALS | Approach lighting system |
| alt | Altitude |
| altn | Alternate |
| ALU | Arithmetic and logic unit |
| AM | Air mobile |
| Amplitude modulation |
| am | ante meridiem (before noon) |
| AMASS | Airport movement area safety system |
| AMC | Automatic modulation control (radio) |
| AMETS | Army meteorological system |
| AMHMS | Advanced magnetic helmet-mounted sight |
| AML | Airfield marking and lighting |
| AMM | Anti-missile missile |
| AMMS | Automatic message management system |
| amp | Amplitude (nav) |
| AMPS | Arctic marine pipelaying system |
| AMS | Acquisition management system |
| American Material Standard |
| AMSL | Above mean sea level |
| AMTD | Adaptive moving target detection (radar) |
| AMTI | Area moving target indication (radar) |
| AMVER | Automated mutual-assistance vessel rescue system |
| AMW | Amphibious warfare |
| Anti-missile warfare |
| ANC | Air Navigation Commission (ICAO) |
| ANKB | Alphanumeric keyboard |
| ANO | Air navigation order |
| ANR | Active noise reduction |
| ANS | Airport navigation service |
| ANSI | American National Standards Institute |
| ANT | Average neap tide |
| ANTM | Admiralty Notice to Mariners |
| ANV | Advanced naval vehicle |
| AO | Adaptive optics |
| AOA | Aerodrome Owners Association |
| Amphibious operations area |
| Angle of attack |
| Army operational architecture (IT) |
| AOB | Air order of battle |
| AOCS | Attitude and orbit control system |
| AOG | Aircraft on ground |
| AOM | Aircraft operating manual |
| AOPA | Aircraft Owners and Pilots Association |
| AOR | Area of responsibility |
| Auxiliary oiler replenishment (vessel) |
| AOTN | Automatic operational telephone network |
| AP | Air publication |
| Ammunition point |
| Anti-personnel |
| Armour-piercing (projectile) |
| APC | Approach control |
| Armoured personnel carrier |
| Automatic phase control |
| APES | Azimuth position and elevation system |
| APFC | Air-portable fuel container |
| APFSDS | Armour-piercing fin-stabilised discarding sabot (ammunition) |
| APFSDS-T | Armour-piercing fin-stabilised discarding sabot-tracer (ammunition) |
| API | Air photo interpretation |
| American Petroleum Institute |
| Application programming interface |
| APIU | Army photo interpretation unit |
| APO | Accident prevention officer (or organisation) |
| Army Post Office |
| APOD | Airport of debarkation |
| APOE | Airport of embarkation |
| APP | Allied procedures publication |
| approx | Approximately |
| APS | Auxiliary power supply |
| APT | Automatically programmed tools (machine tool computer language) |
| APU | Auxiliary power unit |
| AQAP | Allied quality assurance publication |
| AQL | Acceptable quality level |
| AR | Anti-radar |
| Anti-radiation |
| ARCC | Associated rescue co-ordination centre |
| ARCS | Admiralty raster chart service |
| ARLO | Air reconnaissance liaison officer |
| ARM | Advanced RISC machine |
| Anti-radiation missile |
| Availability, reliability, maintainability |
| armd | Armoured |
| armr | Armour |
| ARPA | Automatic radar plotting aid |
| ARPS | Automatic radar plotting system |
| ARQ | Automatic repetition request (radio) |
| ARRV | Armoured repair and recovery vehicle |
| ARTAS | ATC radar and tracker service |
| arty | Artillery |
| ARU | Audio response unit |
| ARV | Armoured recovery vehicle |
| AS | Ammunition storage |
| Anti-submarine |
| Area services |
| ASAAC | Allied Standard Avionic Architecture Council |
| ASAAD | Advanced shipborne area air defence |
| ASACS | Air surveillance and control system |
| ASAPHA | Association of Sea and Port Health Authorities |
| ASAT | Advanced subsonic aerial target |
| Anti-satellite system |
| ASB | Alternate side band (radio) |
| ASC | Air space control |
| ASCAIPS | Army Scaling and Cataloguing Authority initial provisioning system |
| ASCII | American standard code for information interchange |
| ASDA | Accelerated stop distance available |
| ASDE | Airport surface detection equipment |
| ASE | Air safety enforcement |
| ASGW | Air-to-surface guided weapon |
| ASI | Air speed indicator (aircraft) |
| Armaments standardisation and interoperability |
| ASIC | Application-specific integrated circuit |
| ASK | Amplitude shift keying |
| ASL | Above sea level |
| ASM | Air-to-surface missile |
| Airfield survival measures |
| Airspace management |
| Anti-ship missile |
| ASMA | Air space management aid |
| ASMD | Anti-ship missile defence |
| ASMI | Airport surface movement indicator (radar) |
| ASNO | Approach sequence number |
| ASOC | Air support operations centre |
| ASP | Ammunition supply point |
| Application service provider |
| ASPJ | Airborne self-protection jammer |
| ASR | Airfield surveillance radar |
| Area surveillance radar |
| Automatic send/receive (terminal) |
| ASROC | Anti-submarine rocket |
| ASRS | Aviation safety reporting system |
| ASS | Airport support services |
| ASSM | Anti-surface ship missile |
| ASST | Anti-surface surveillance and targeting |
| ASSU | Air support signal unit |
| ASSY | Assembly |
| AST | Average spring tide |
| ASTM | American Society for Testing and Materials |
| astn | Astern |
| ASTOR | Airborne stand-off radar |
| ASTOVL | Advanced short take-off and vertical landing (aircraft) |
| ASU | Air start unit (aircraft) |
| ASUW | Anti-surface warfare |
| ASV | Anti-surface vessel |
| Armoured security vehicle |
| ASW | Anti-submarine warfare |
| ASWC | Anti-submarine warfare commander |
| ASWE | Admiralty Surface Weapons Establishment |
| AT | Anti-tank |
| ATA | Actual time of arrival |
| Air Transport Association |
| ATAA | Air Transport Auxiliary Association |
| ATARS | Advanced tactical air reconnaissance system (USA) |
| ATAS | Active towed array sonar |
| ATBM | Anti-tactical ballistic missile |
| ATC | Air Training Corps |
| Air traffic control |
| Armoured troop carrier |
| Automatic tuning control |
| ATCA | Allied Tactical Communications Agency |
| ATCC | Air traffic control centre |
| ATCO | Air traffic control officer |
| ATCS | Air traffic control system |
| ATCV | Anti-tank combat vehicle |
| ATD | Actual time of departure |
| Aircraft training device |
| Along-track distance (nav) |
| ATDS | Airborne tactical data system |
| ATE | Automatic test equipment |
| ATF | Advanced tactical fighter (USA) aircraft |
| ATFM | Air traffic flow management |
| ATGW | Anti-tank guided weapon |
| ATIS | Air traffic information service |
| Automated terminal information system |
| Atl | Atlantic |
| ATLAS | Abbreviated test language for all systems (computer) |
| Abbreviated test language for avionic systems |
| Automated temperature line acquisition system |
| ATM | Air task message |
| Air traffic management |
| Anti-tank missile |
| Asynchronous transfer mode (data) |
| atm | Atmosphere (pressure) |
| ATMC | Admiralty transmitting magnetic compass |
| ATN | Administrative telephone network |
| ATO | Actual time over |
| ATOA | Air Transport Operators Association |
| ATOC | Acoustic thermometry of ocean climate |
| ATOS | Air traffic operations support |
| ATOTN | Air traffic operational telephone network |
| ATPL | Airline transport pilot´s licence |
| ATR | Air-transportable racking |
| Automatic target recognition |
| ATRS | Air traffic radar service |
| ATS | Air traffic service |
| Amphibious transport ship |
| ATSA | Air traffic services administration |
| ATSU | Air traffic service unit |
| ATT | Admiralty tide tables |
| att | Attached |
| ATTAS | Advanced technologies testing aircraft system |
| ATU | Antenna tuning unit |
| ATZ | Airport traffic zone |
| AU | Accounting unit |
| AUI | Adaptive user interface (computers) |
| AUM | Air-to-underwater missile |
| AUP | Acceptable use policy (computers) |
| AUV | Autonomous underwater vehicle |
| AUW | All-up weight (aircraft) |
| AUWE | Admiralty Underwater Weapons Establishment |
| AV | Audio-visual |
| AVAD | Automatic voice alerting device |
| AVC | Automatic volume command |
| avgas | Aviation gasoline |
| AVIT | Audio-visual instruction technique |
| AVLB | Armoured vehicle-launched bridge |
| AVMRL | Armoured vehicle-mounted rocket launcher |
| AVP | Aviation publication |
| AVR | Armoured vehicle, reconnaissance |
| Automatic voltage regulator |
| AVS | Anti-virus software |
| AVT | Automatic video tracker |
| avtag | Aviation fuel (gasoline/kerosene) |
| avtur | Aviation fuel (kerosene jet fuel) |
| AW | All-weather |
| Amphibious warfare |
| Archipelagic waters |
| AWACS | Airborne warning and control system |
| AWD | Airworthiness Division |
| AWHQ | Alternate war headquarters |
| AWO | All-weather operations (aircraft) |
| AWOP | All-weather operations panel (ICAO) |
| awy | Airway |
| AXBT | Air-launched expendable bathythermograph |
| az | Azimuth |
