| Abbreviation | Definition |
|---|---|
| ATM | Amateur Telescope Makers |
| ATM | American Tool and Mold |
| ATM | Applied Technologies Manufacturing Company |
| ATMAC | Advanced Technology Manufacturing and Assembling City |
| ATMC | Atlantic Telephone Membership Corporation |
| ATMI | Atlantic Trading Marketing Incorporated |
| ATO | Approved Training Organization |
| ATO | Aquitaine Total Organico |
| ATO | Assemble To Order |
| ATOL | Affordable Technolgy On-Line |
| ATP | American Tennis Psychologists |
| ATPA | Associated Third Party Administrators |
| ATR | Advanced Technologies and Research |
| ATR | Avion de Transport Regional |
| ATRIM | Advanced Technical Research & Innovation for Mankind |
| ATS | Alenco Tool Supply, Chicago, Illinois |
| ATS | Amalgamated Taxis Services |
| ATS | Austin Tele Services |
| ATSC | Administrative Technology Service Center |
| ATSC | Advanced Technology Systems Company |