| Abbreviation | Definition |
|---|---|
| ATM | Advanced Test Module |
| ATM | Asychronous Transfer Mode |
| ATM | Automated Timing Mechanism |
| ATM | Automatic Timing Mechanism |
| ATNE | All Tech Neek Electronics |
| ATP | Autotransformer Thermal Protection |
| ATPG | Automatic Test Pattern Generation |
| ATR | Antenna Test Range |
| ATR | Attenuated Total Reflectance |
| ATS | Absolute Time Sequence |
| ATS | Automatic Transfer Switch |
| ATT | Attenuated |
| Att | Attenuation |
| ATTON | Attenuation On (a reduction in the amplitude level of the outputted sound) |
| ATU | Air Tower Unit |
| ATU | Antenna Tuning Unit |
| ATV | Analog television |
| ATVM | Automatic Ticket Vending Machine |
| ATZP | Awakening To Zero Point |
| AU | Arbitrary Unit |