| PAO | Panathinaikos Athlitikos Omilos 
| Others |
| PAO | Passport Advantage Online
| Others |
| PAO | Period After Opening
| Others |
| PAO | Periodicals Archive Online
| Others |
| PAO | Perpetual American Options
| Others |
| PAO | Person Action and Object
| Others |
| PAO | Person Action Object
| Others |
| PAO | Personal Air Outlet
| Others |
| PAO | phenylarsine oxide
| Others |
| PAO | Philippine Academy of Ophthalmology
| Others |
| PAO | Phoenix Afrobeat Orchestra
| Others |
| PAO | Picchetto Armato Ordinario
| Others |
| PAO | Pierre Auger Observatory
| Others |
| PAO | Planed All Over
| Others |
| PAO | Planetary Activation Organization
| Others |
| PAO | Polarized Atomic Orbital
| Others |
| PAO | Poly Alfa Olefin
| Others |
| PAO | Poly Alpha Olefin
| Others |
| PAO | Poly Alpha Olefine
| Others |
| PAO | Poly alpha olefins
| Others |
| PAO | PolyAlphaOlefin
| Others |
| PAO | Portable Astronomical Observatory
| Others |
| PAO | Post Academisch Onderwijs
| Others |
| PAO | Post Arrival Orientation
| Others |
| PAO | Power Assisted Optimization
| Others |
| PAO | Pro Athletes Outreach
| Others |
| PAO | Programs Abroad Office
| Others |
| PAO | Propoganda And Arrogance Office
| Others |
| PAO | Provider Access Organization
| Others |
| PAO | Public Adviser's Office
| Others |
| PAO | Public Affairs Office
| Others |
| PAO | Public Affairs Officer
| Others |
| PAO | Public Assistance Officer
| Others |
| PAO | Public Autopsy Office
| Others |
| PAO | Publication Assistee Par Ordinateur
| Others |