| Acronym | Definition |
|---|
| OAO | Office of Advocacy and Outreach (USDA) |
| OAO | Office of Administrative Operations (US DOC) |
| OAO | Owned and Operated |
| OAO | Orbiting Astronomical Observatory |
| OAO | Over and Out |
| OAO | One And Only |
| OAO | Overall Opinion (marketing) |
| OAO | Ontario Association of Orthodontists |
| OAO | Ontario Association of Optometrists |
| OAO | Opticians Association of Ohio |
| OAO | Oregon Academy of Ophthalmology |
| OAO | Orthogonalized Atomic Orbital |
| OAO | Office of Appellate Operations (US Social Security Administration) |
| OAO | Otkrytoe Aktsionernoe Obschestvo (Russian: Open Joint Stock Corporation) |
| OAO | Orbital Analysis Officer |
| OAO | One Among Others |
| OAO | Other Authorised Operator (telecommunications) |
| OAO | Objective Area Officer |