| Abbreviation | Definition |
|---|---|
| ARM | Armorer |
| ARM1 | Aviation Radioman Petty Officer First Class |
| ARM2 | Aviation Radioman Petty Officer 2nd Class |
| ARM3 | Aviation Radioman Petty Officer 3rd Class |
| ARMAC | Aviation Radioman (combat Aircrewman) |
| ARNO | Association of Royal Naval Officers |
| AROTC | Army Reserve Officer Training Corps |
| ARPN | Aircraft and Related Procurement Navy |
| ART1 | Aviation Radio Technician Petty Officer 1st Class |
| ART2 | Aviation Radio Technician Petty Officer 2nd Class |
| ART3 | Aviation Radio Technician Petty Officer 3rd Class |
| ARTIF | Artificer |
| AS | Able Seaman |
| AS | Apprentice Seaman |
| AS1 | Aviation Support Equipment Technician Petty Officer 1st Class |
| ASA | Apprentice Seaman (aviation) |
| ASAR | Apprentice Seaman (aviation Rigger) |
| ASC | Aviation Support Equipment Technician Chief Petty Officer |
| ASCK | Assistant Cook |
| ASCM | Aviation Support Equipment Technician Master Chief Petty Officer |