| Abbreviation | Definition |
|---|---|
| ARMS | Arc flash Reduction Maintenance Switch |
| ARP | Azimuth Reset Pulse |
| ARPA | Advanced Research Projects Agency |
| ARQ | Automatic Receiver Quieting |
| ARS | Angle-Resolved Scattering |
| ARS | Auto Reclosing Scheme |
| ART | Applied Research Technology |
| ART | Applied Research & Technology |
| ARTS | Automatic Range Transponder System |
| AS | Active Serial |
| As | Arsenic |
| ASAP | Accurate Sensitive And Precise |
| ASAP | Adaptive Sampling And Prediction |
| ASAP | Advanced Stepper Application Program |
| ASC | ADPCM (Adaptive Differential Pulse Code Modulation) Stereo C |
| ASDL | American Standard Digital Line |
| ASE | Amplified Spontaneous Emission |
| ASE | Amplified Stimulated Emission |
| ASEET | Associate of Science in Electrical Engineering Technology |
| ASES | Audio Sound Erase Static |