| Abbreviation | Definition |
|---|---|
| ACR | Active, Confirmed, Registered |
| ACRA | Australasian Conference on Robotics and Automation |
| ACRM | American Congress of Rehabilitation Medicine |
| ACRS | Asian Conference on Remote Sensing |
| ACSAC | ACSACAnnual Computer Security Applications Conference |
| ACSC | Alabama Christian Sports Conference |
| ACSC | Ateneo Corporate Sustainability Conference |
| ACSC | Australian Computer Science Conference |
| ACSE | Automatic Control and System Engineering |
| ACSM | American Congress of Surveying and Mapping |
| ACSSC | Asian Cinema Studies Society Conference |
| ACSSC | Asilomar Conference on Signals Systems and Computers |
| ACTE | Annual Convention and Career Tech Exposition |
| ACTS | Adoration Confession Thanksgiving and Supplication |
| ACUS | Administrative Conference of the United States |
| ACUU | Aging Concerns Unite Us |
| ACVC | Atlantic Coast Veterinary Conference |
| ACVG | Armagh Conference of Voluntary Groups |
| ACVR | Annual Conference on Vaccine Research |
| ACVR | Annual Conference on Vaccinology Research |