| %AC | percent area coverage |
| A&A | Assessment and Authorization |
| A&O | Acquisition and Operations |
| A&R | Applicable and Reference |
| A&S | Analysis and Simulation |
| A/D | analog to digital |
| A | Ampere(s) |
| Aa | Availability achieved |
| AA | Archive and Access |
| AA | Assistant Administrator (NOAA) |
| AA | Associate Administrator (NASA) |
| AAA | aerosol, air chemistry, and air quality |
| AART | Algorithm Action Review Team |
| AAS | American Astronautical Society |
| AAS | Antenna Administrative Server |
| AATSR | Advanced Along-Track Scanning Radiometer |
| AAWDS | Advanced Baseline Imager (ABI) Algorithm Working Group (AWG)/University of Wisconsin (UW) Data Set |
| AAWU | Alaska Aviation Weather Unit |
| ABI | Advanced Baseline Imager |
| ABIE | Advanced Baseline Imager Emulator |
| ABISS | Advanced Baseline Imager Star Selection |
| ABL | Allocated Baseline |
| ABPL | As-Built Parts List |
| ABR | Area Border Router |
| AC | Above Clouds |
| AC | Access Control (security) |
| AC | Accomplishment Criteria |
| AC | Active Cooler |
| AC | Actual Cost |
| AC | Area Coverage |
| ACA | Associate Contractor Agreement |
| ACC | Attitude Control Console |
| ACCS | Accounting Code Classification Structure |
| ACE | Advanced Composition Explorer |
| ACK | acknowledgement |
| ACL | Access Control List |
| ACM | Advanced Baseline Imager (ABI) Clear Sky Mask |
| ACO | Administrative Contracting Officer |
| ACP | Access Control Plan |
| ACRN | Accounting Classification Reference Number |
| ACS | Attitude Control System |
| ACSPO | Advanced Clear-Sky Processor for Oceans |
| ACT | ABI Cloud Type |
| ACT | Activation and Characterization Test |
| ACTD | Advanced Concept Technology Demonstration |
| ACTE | Auxiliary Communication Test Equipment |
| ACU | Antenna Control Unit |
| ACWP | Actual Cost of Work Performed |
| ACWS | Actual Cost of Work Scheduled |
| ADAM | Automatic Dynamic Analysis of Mechanical Systems (MSC Software) |
| ADC | Analog to Digital Converter |
| ADD | Algorithm Description Document |
| ADDE | Abstract Data Distribution Environment (McIDAS data server) |
| ADEB | Algorithm Development Executive Board |
| ADIS | Angle Detecting Inclined Sensor |
| ADL | AER Development Lab |
| ADM | Aerosol Detection Product |
| ADM | Angular Distribution Model |
| ADMP | Algorithm Development Management Plan |
| ADO | Algorithm Development Organization |
| ADP | Analog Detection Product |
| ADPL | As-Delivered Parts List |
| ADR | Algorithm Discrepancy Report |
| ADR | Algorithm Design Review |
| ADRR | Algorithm Design Review Report |
| ADRS | Ancillary Data Review System |
| ADS | Auxiliary Distribution System |
| ADS | Alternative Distribution Switch |
| ADT | Advanced Dvorak Technique |
| AE | Autumnal Equinox |
| AE | Ångström exponent |
| AECS | Automated Entry Control System |
| AEHF | Advanced Extremely High Frequency |
| AEL | Active Event List |
| AER | Atmospheric & Environmental Research Inc. |
| AERI | Atmospheric Emitted Radiance Interferometer |
| AERONET | AErosol RObotics NETwork |
| AEROSE | Aerosol and Ocean Science Expedition |
| AES | Advanced Encryption Standard |
| AES | Automated Export System |
| AET | Aerospace Engineering Technician |
| AET | Antenna Element Tracking |
| AETD | Applied Engineering and Technology Directorate |
| AF | Assured Forwarding |
| AF | Automation Framework |
| AF | award fee |
| AFM | Anti-alias Filter Module |
| AFRB | Award Fee Review Board |
| AFRL | Air Force Research Laboratory |
| AFSCM | Air Force Space Command Manual |
| AFSPCMAN | Air Force Space Command Manual |
| AFSCN | Air Force Space Command Network |
| AFSPC | Air Force Space Command |
| AFWA | Air Force Weather Agency |
| AG | as generated |
| AGE | Aerospace Ground Equipment |
| AGI | Analytical Graphics, Inc. |
| AGM | Annual Guidance Memorandum |
| AGMA | American Gear Manufacturers Association |
| AGO | Acquisition and Grants Office (NOAA) |
| AGS | Alaska Ground System |
| AH | Authorization Header |
| AHI | Advanced Himawari Imager |
| AI | Action item |
| AI | Availability - Inherent |
| AI&T | assembly, integration, and test |
| AIAA | American Institute of Aeronautics & Astronautics |
| AIADD | Algorithm Interface and Ancillary Data Description |
| AIM | ABI Ice Motion |
| AIP | Aerosol Imagery Products |
| AIP | Agreement-in-Principle |
| AIR | Action Item Review |
| AIRS | Atmospheric Infrared Sounder |
| AIS | Automated Instrument Scheduling |
| AISC | American Institute of Steel Construction |
| AIT | Algorithm Integration Team |
| AIT | Assembly Integration and Test |
| AITA | ABI Ice Thickness and Age |
| AITP | Algorithm Implementation and Test Plan |
| AJ | ArcJet |
| AJAX | Asynchronous JavaScript And XML |
| ALC | Automatic/Auto-Level Control |
| ALI | EO-1 Advanced Land Imager |
| AlloID's | Allocation identifications |
| ALT | Accelerated Life Testing |
| AMCS | Articulation Motor Control System |
| AMM | Analog Magnetometer Module |
| AMO | Air Mass Zero |
| AMOS | Automatic Meteorological Observing Station |
| AMS | Agent Management Services |
| AMS | American Meteorological Society |
| AMSC | American Mobile Satellite Corporation |
| AMSR-E | Advanced Microwave Scanning Radiometer - Earth Observing System |
| AMSU | Advanced Microwave Sounding Unit |
| AMV | Atmospheric Motion Vectors |
| ANCF | AWIPS Network Control Facility |
| AND | Alpha-Numeric Display (part of SDGUD suite) |
| ANGEN | Analytic Generation of Spectral Response |
| ANSI | American National Standards Institute |
| ANSI/EIA | ANSI/Electronics Industry Associates |
| ANSI/ISO | ANSI/International Organization of Standards |
| ANT | Antenna/Antenna Systems |
| ANTC | Antenna Station Control |
| AO | Active Object |
| AO | Active Operational |
| AO | Aft Optics |
| AO | Announcement of Opportunity |
| Ao | Availability (Operational) |
| AoA | Analysis of Alternatives |
| AOC | Active Object Class |
| AOD | Aerosol Optical Depth |
| AODR | Authorizing Official’s Designated Representative |
| AODT | Advanced Objective Dvorak Technique |
| AOL | Atmosphere Oceans and Land |
| AOP | Annual Operating Plan |
| AOS | Acquisition of Signal |
| AOS | Advanced Orbiting System |
| AP | Advanced Platform |
| AP | Algorithm Package |
| APA | Allowance for Program Adjustment |
| API | Application Programming Interface |
| APID | Application Process Identifier |
| APL | Applied Physics Laboratory (Johns Hopkins University) |
| APM | Assistant Project Manager |
| APO | Annual Operating Plan |
| APOLLO | AVHRR Processing Scheme over Land, Clouds and Ocean |
| APPF | Astrotech Payload Processing Facility |
| APPL | Academy of Program and Project Leadership |
| APS | Active Pixel Sensor |
| APS | Aerosol Particle Size |
| AQ | Air Quality |
| AQC | Automatic Quality Control |
| AQPG | Air Quality Proving Ground |
| AR | Acceptance Review |
| AR | as required |
| ARB | Acquisition Review Board |
| ARC | Ames Research Center |
| ARES | Applied Research and Engineering Sciences |
| ARM | Atmospheric Radiation Measurement Program (U.S. Department of Energy) |
| ARR | Algorithm Readiness Review |
| ART | Anomaly Reporting and Tracking |
| ARTCC | Air Route Traffic Control Center |
| ARTEMIS | Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon's Interface with the Sun |
| ARTS | ASRC Research and Technology Solutions |
| AS | Advanced Server |
| AS | Antenna System |
| ASA | Assistant Secretary for Administration |
| ASAR | Antenna System Acceptance Review |
| ASCAT | Advanced Scatterometer |
| ASCII | American Standard Code for Information Interchange |
| ASCOUTS | A2100 Satellite Check Out and Universal Test System |
| ASCR | Antenna Station Certification Review |
| ASD | Acceleration Spectral Density |
| ASDP | Alliance for Supplier Diversity Professionals |
| ASDR | Antenna System Delivery Review |
| ASE | Asset Sustainability Edition |
| ASI | Application Specific Input |
| ASIC | Application Specific Integrated Circuits |
| ASIS | Antenna System Interface Simulator |
| ASIST | Advanced Spacecraft Integration and Systems Test |
| ASM | Acquisition Strategy Meeting |
| ASN | Autonomous System Number |
| ASO | Application Specific Output |
| ASO | Astrotech |
| ASOC | Atlas Spaceflight Operations Center |
| ASOS | Automated Surface Observing System |
| ASP | Attitude Sensor Package |
| ASP | Aerosol Size Parameter |
| ASPB | Advanced Satellite Products Branch |
| ASPD | Assistant System Program Director |
| ASQC | American Society for Quality Control |
| ASRC | Arctic Slope Regional Corporation |
| ASRS | Antenna System Requirements Specification |
| AST | All Software Testbed |
| ASTER | Advanced Spaceborne Thermal Emission and Reflection radiometer (EOS) |
| ASTM | American Society for Testing and Materials |
| ASTMGT | Asset Management |
| ASU | Advanced Settings Utility |
| ASU | Arizona State University |
| AT | Action Team |
| AT | Awareness and Training |
| ATBD | Algorithm Theoretical Basis Document |
| ATC | Advanced Technology Center |
| ATC | Assurance Technology Corporation |
| ATCF | Air Traffic Control Association |
| ATCF | Automated Tropical Cyclone Forecast |
| ATD | Advanced Technology Development |
| ATK | Alliant Techsystems Incorporated |
| ATIP | Algorithm and Test Implementation Plan |
| ATLO | Assembly, Test and Launch Operations |
| ATM | Asynchronous Transfer Mode |
| ATO | Authority To Operate |
| ATP | Acceptance Test Procedure |
| ATP | Aeronautics Test Program |
| ATP | Algorithm Test and Performance |
| ATP | Authority To Proceed |
| ATR | Alternative Technical Representative |
| ATRR | Acceptance Test Readiness Review |
| ATS | Absolute Time Sequence |
| AU | Astronomical Unit |
| AV | Anti-Virus |
| AVD | Active Vibration Damping |
| AVHRR | Advanced Very High Resolution Radiometer |
| AVI | Airborne Visible Imager |
| AVIRIS | Airborne Visible Infrared Imaging Spectrometer |
| AVS | Angular Velocity sensor |
| AVVID | Architecture for Voice, Video and Integrated Data |
| AWA | Antenna Wing Assembly |
| AWC | Aviation Weather Center (NWS) |
| AWE | Alert, Warning and Event |
| AWG | Algorithm Working Group |
| AWG | Arbitrary Waveform Generator |
| AWiFS | Advanced Wide Field Sensor |
| AWIPS | Advanced Weather Interactive Processing System |
| AWT | Aviation Weather Test Bed |