| AAT | American Accent Training |
|---|---|
| ABT | Air Combat Training |
| AT | Appalachian Trail |
| ATA | Allegheny Trail Alliance |
| ATC | Air Training Command |
| ATC | Air Training Corps |
| ATC | Athletic Trainer Certified |
| ATC | Autodesk Authorised Training Centre (skr.) |
| ATC | Automatic Train Control |
| ATTO | Assistive technology training online |