| Abbreviation | Definition |
|---|---|
| AT | Alpine Touring |
| AT | Assay Technologies |
| AT&T | American Telephone and Telegraph |
| ATA | American Towing Alliance |
| ATA | American Trans Air |
| ATAB | Association of Travel Agents of Bangladesh |
| ATAC | Airborne Tactical Advantage Company |
| ATAC | Avionics Test And Analysis Corporation |
| ATAO | Altair International Corporation |
| ATAT | Arbeitsgemeinschaft für Total Abgehobene Technologie |
| ATBC | Athens Bancshares Corporation |
| ATBC | Australian Tamil Broadcasting Corporation |
| ATC | A Touch of Class |
| ATC | Advanced Telecommunications Corporation |
| ATC | Advanced Thermodynamics Corporation |
| ATC | Aluminum Trailer Company |
| ATC | American Tractor Company |
| ATC | American Transmission Company |
| ATC | Apex Tool Company |
| ATC | Auburn Towing Company |