| OAO | On-line Analog Output | 联机模拟输出 |
| OAO | Orbiting Astronomical Observatory | 欧奥（轨道天文观测站） |
| OAO | Opticians Association of Ohio | 俄亥俄州光学协会 |
| OAO | Ontario Association of Orthodontists | 安大略省正畸医师协会 |
| OAO | Ontario Association of Optometrists | 安大略省验光师协会 |
| OAO | Otkrytoe Aktsionernoe Obschestvo (Russian: Open Joint Stock Corporation) | Otkrytoe Aktsinernoe Obschestvo（俄语：开放式股份公司） |
| OAO | Orthogonalized Atomic Orbital | 正交化原子轨道 |
| OAO | Orbital Analysis Officer | 轨道分析官 |
| OAO | Office of Academic Opportunities | 学术机会办公室 |
| OAO | Original Art Only | 仅原创艺术 |
| OAO | Owned and Operated | 拥有和经营 |
| OAO | One And Only | 唯一 |
| OAO | Over and Out | 结束并退出 |