| APAO | Acute Peripheral Arterial Occlusion 
| Others |
| APAO | Aggregate Producers Association of Ontario
| Others |
| APAO | AgriEnergy Producers Association of Ontario
| Others |
| APAO | AgriEnergy Producers' Association of Ontario
| Others |
| APAO | Alternative Policy Advisory Organizations
| Others |
| APAO | Amorphous Poly alpha olefins
| Others |
| APAO | Archaeology and Physical Anthropology in Oceania
| Others |
| APAO | Asia Pacific Academy of Ophthalmology
| Others |
| APAO | Asia Pacific Automotive Operations
| Others |
| APAO | Asia-Pacific Academy of Ophthalmology
| Others |
| APAO | Asian Pacific Astronomy Olympiad
| Others |
| APAO | Asphalt Pavement Association of Oregon
| Others |
| APAO | Association of Physician Assistants in Oncology
| Others |
| APAO | Association of Private Airport Operators
| Others |