| Abbreviation | Definition |
|---|---|
| AMS | Aeospace Material Specification |
| AMS | Anti-Mugging Stick |
| AMS | Autogas Management System |
| AMSAC | ATWS Mitigation System Actuation Circuitry |
| ANCB | ANimal design CheckBook cover |
| ANCE | National Association of Normalization and Certification of the Electrical Sector (Mexico) |
| ANF | Abercrombie and Fitch |
| AO | Antique and Old |
| AOAC | Always On, Always Connected |
| AOD | Automatic OverDrive |
| AODD | Air Operated Double Diaphragm |
| AOP | American Office Products |
| AOPD | American Office Products Distributors |
| AOPP | Advanced Oxidation Protein Products |
| AOPP | Affecting Oxidative Protein Products |
| AOSS | Airstation Onetouch Secure System |
| AOSS | Alfa Omega Suspension System |
| AP | Absolutely Perfect |
| AP | Approved Product |
| AP | Architectural Products |