| Abbreviation | Definition |
|---|---|
| ANZAC | Australia New Zealand Allied Command |
| ANZAC | Australian and New Zealand Army Corps |
| ANZUS | Australia, New Zealand, United States |
| AO | Action Officer |
| AO | Administration Officer |
| AO | administrative occupations |
| AO | Administrative Officer |
| AO | Aerial Observer |
| AO | Agent Orange |
| AO | Air Officer |
| AO | Approval Order |
| AO | Area of Operation |
| AO | Area of Operations |
| AO | Army Orders |
| AO | Authorizing Official |
| AO | Aviation Ordnanceman |
| AO | Aviatsionnaya Oskolochnyang (aircraft fragmentation ammunition) |
| AO&M | Administration, Operation, and Maintenance |
| AOA | Abbreviated Operational Assessment |
| AOA | Add- On Armor |