| P.I.O. | Press Information Officer 
| Others |
| P.I.O. | Public Information Officer
| Others |
| PIO | Dodge Pioneer
| Others |
| PIO | Pacific Indian Ocean
| Others |
| PIO | Pacific Islander Outreach
| Others |
| PIO | Pain In the Oopher
| Others |
| PIO | Pakistani Intelligence Operatives
| Agency, Intelligence Agency |
| PIO | Paper In Oil
| Others |
| PIO | Parallel Input Output
| Others |
| PIO | Parrallel Input And Output
| Others |
| PIO | Parts In One
| Others |
| PIO | Pass It On
| Others |
| PIO | Past Inputs and Outputs
| Others |
| PIO | Payload Integration Plan
| Others |
| PIO | People Improvement Organization
| Others |
| PIO | Periodicals Index Online
| Others |
| PIO | Person of Indian Origin
| Others |
| PIO | Persons of Indian Origin
| Others |
| PIO | Pilot Induced Oscillation
| Others |
| PIO | Pilot Induced Oscillations
| Others |
| PIO | Pilot-Induced Oscillation
| Others |
| PIO | Pisco, Peru
| Others |
| PIO | Port Input Output
| Others |
| PIO | Port Installed Option
| Others |
| PIO | Port Installed Options
| Others |
| PIO | Prazsky Improvizacni Orchestr Prague Improvisation Orchestra
| Others |
| PIO | Prefix Information Option
| Others |
| PIO | Press and Information Office
| Others |
| PIO | Principle Investigating Officer
| Others |
| PIO | Process Impact And Outcome
| Others |
| PIO | Processor Input Output
| Others |
| PIO | Professional Instructors Organization
| Others |
| PIO | Progesterone In Oil
| Others |
| PIO | Program Information Office
| Others |
| PIO | Programmed Input Output
| Others |
| PIO | Programmed Input/Output
| Others |
| PIO | Property Investment Option
| Others |
| PIO | Protected Intending Occupier
| Others |
| PIO | Protocol Information Office
| Others |
| PIO | Public Information Office
| Others |