| Acronym | Meaning |
 | ARPS | Advanced Regional Prediction System |
 | ARR | Association For Radiation Research |
 | ARRL | Amateur Radio Relay League |
 | ARS | American Rocket Society |
 | ARSR | Air Route Surveillance Radar |
 | ART | Aqueous Recycle Technologies |
 | ARTCC | Air Route Traffic Control Center |
 | ARW | Advanced Research Workshop |
 | ARWG | Atmospheric Radiation Working Group |
 | AS&E | American Science And Engineering |
 | ASALM | Advanced Strategic Air Launched Missile |
 | ASAP | Automated Shipboard Aerological Program |
 | ASAP | As Soon As Possible |
 | ASAP | Ariane Structure For Auxiliary Payloads |
 | ASAP | Aerospace Safety Automation Program |
 | ASAP | Aerospace Safety Advisory Panel |
 | ASAP | Accelerated Situational Awareness Prototype |
 | ASAS | Advanced Solid-State Array Sensor |
 | ASASP | Active Scattering Aerosol Spectrometer |
 | ASASP | Advanced Solid-State Array Sensor |
 | ASC | Advanced Science Computer |
 | ASC | ASTER Steering Committee |
 | ASCE | American Society Of Civil Engineers |
 | ASCENT | Atmospheric Sounding |
 | ASCII | American Standard Code For Information Interchange |
 | ASCOT | Atmospheric Studies In Complex Terrain |
 | ASD | Aircraft Situation Display |
 | ASDAR | Aircraft-to-Satellite Data Relay |
 | ASE | Air Sea Experiment |
 | ASE | Amplified Spontaneous Emission |
 | ASEP | Accident Sequence Evaluation Program |
 | ASER | Annual Site Environmental Report |
 | ASF | Alaska SAR Facility |
 | ASH CAN | Project Ash Can |
 | ASHAA | Asbestos In Schools Hazard Abatement Act |
 | ASHOE | Airborne Southern Hemisphere Ozone Experiment |
 | ASHRAE | American Society Of Heating |
 | ASI | Advanced Simulation Initiative |
 | ASI | Agenzia Spaxiale Italiano |
 | ASIC | Application Specific Integrated Circuit |
 | ASIS | American Society For Industrial Security |
 | ASIWPCA | Association Of State & Interstate Water Pollution Control Administrators |
 | ASL | Atmospheric Science Laboratory |
 | ASL | Above Sea Level |
 | ASL | American Sign Language |
 | ASLB | Atomic Safety Licensing Board |
 | ASM | American Society For Metals |
 | ASME | American Society Of Mechanical Engineers |
 | ASNT | American Society For Nondestructive Testing |
 | ASOS | Automated Surface Observing System |