| Abbreviation | Definition |
|---|---|
| ATIA | Association of Translators and Interpreters of Alberta |
| ATIA | Australian Taxi Industry Association |
| ATIO | Association of Translators and Interpreters of Ontario |
| ATLA | American Theological Library Association |
| ATLA | Association of Teachers of Lipreading to Adults |
| ATLA | Association of Trial Lawyers of America |
| ATOAI | Adventure Tour Operators Association of India |
| ATOC | Association Train Operating Companies |
| ATOP | Association Of Tour Operators To Portugal |
| ATPM | Association of Teachers and Preventive Medicine |
| ATRA | Alternative Transportation Recreational Association |
| ATRA | American Thailand Ridgeback Association |
| ATRA | American Therapeutic Recreation Association |
| ATRA | The Automatic Transmission Rebuilders Association |
| ATS | American Thoracic Society |
| ATSI | Association Of Thai Software Industry |
| ATSM | Association of Telecommunications Systems Management |
| ATSP | Association of Telehealth Service Providers |
| ATSPR | Australian Trades Service Professionals Registry |
| ATSPR | Australian Trades & Service Professionals Registry |