| Abbreviation | Definition |
|---|---|
| AOM(s) | acousto-optic modulator(s) |
| AOPP | Atmospheric Oceanic and Planetary Physics |
| AP | Anti-Proton |
| AP | Applied Physics |
| APAM | Applied Physics and Applied Math |
| APAM | Applied Physics and Applied Mathematics |
| APCC | Astro Physics Command Center |
| APCTP | Asia Pacific Center for Theoretical Physics |
| APCTP | Asia Pacific Centre for Theoretical Physics |
| APD | Action Potential Duration |
| APE | Actionscript Physics Engine |
| APGR | Association for Pushing Gravity Research |
| APIF | Astropartical Physics International Forum |
| APIF | Astroparticle Physics International Forum |
| APIG | Applied Physics Instrumentation Group |
| APL | Advanced Physics Laboratory |
| APL | Applied Physics Letters |
| APM | Absolute Proper Motion |
| APM | Associated Particle Method |
| APOP | Automatic Particle Orientation Procedure |