| Abbreviation | Definition |
|---|---|
| 5E | Fifth Edition, Dungeons and Dragons |
| A51 | Area 51 |
| AA | Amazon Alliance |
| AAAGH | Alien Assignment Agency General Headquarters |
| AAF | Alien Ant Farm |
| AAT | Armored Assault Tank |
| ABT | Anglo Babylonian Time |
| AC | Asheron's Call |
| ACIO | Alien Contact Intelligence Organization |
| ACMG | Arthur Clarke Mars Greenhouse |
| ACMP | Anime Colony Merecenary Police |
| ACN | Another Cult Network |
| ACRONYM | Arcane Capturing Rod Of Never Yielding Mystery |
| ACTS | Artificially Cutting-edge Tracking System |
| AD | Alliance of Destructors |
| AD | Ancient Dragon |
| ADAM | Armored Defense and Artillery Mechanism |
| ADAM | Assemble, Dammit, Assemble Me |
| ADAM | Autonomous Digital Assault Microbe |
| ADB | Android Debug Bridge |