| Acronym | Definition |
|---|
| RIO | Rio De Janeiro, Rio De Janeiro, Brazil (Airport Code) |
| RIO | Risk, Issues, and Opportunities (various locations) |
| RIO | Remote Input Output |
| RIO | Reference Identifier Object |
| RIO | Ram Input Output |
| RIO | Rock in Opposition (musical genre) |
| RIO | Radar Intercept Officer |
| RIO | RapidIO (Interconnect Architecture) |
| RIO | Regionaal Indicatie Orgaan (Dutch: Regional Indication Body; health care) |
| RIO | Rimonabant in Obesity |
| RIO | Reconfigurable Input/Output |
| RIO | Reference Interconnection Offer |
| RIO | Restore Iraqi Oil (US Army mission) |
| RIO | Reintegration of Offenders |
| RIO | Remote Input/Output |
| RIO | Right, I'm Off |
| RIO | Research Innovation Office (various locations) |
| RIO | Régie des Installations Olympiques |
| RIO | Reusable Information Object |
| RIO | Reshaping the International Order (book) |
| RIO | Regional Information Officer (USACE) |
| RIO | Retirement Income Option (various organizations) |
| RIO | Relevé d'Identité d'Opérateur (French: Statement of Identity Operator) |
| RIO | Resampled Inference of Orthologs |
| RIO | Remote Infrastructure Operations |
| RIO | Réseau Intertropical d'Ordinateurs (French: Intertropical Network of Computers) |
| RIO | Research Instruction Online |
| RIO | Reverse Implied Odds (Poker) |
| RIO | Reverse Implement Option (riding lawnmowers) |
| RIO | Roma Initiatives Office (Open Society Institute) |
| RIO | Random Insanity Online (website) |
| RIO | Resolution Independent Object(s) |
| RIO | Reporting In & Out |
| RIO | Ribbonized Organized Integrated (aircraft wiring) |
| RIO | Regional Inspection Officer (India) |
| RIO | Random Early Discard with In/Out (algorithm) |
| RIO | Remote Inside Option (Compaq) |
| RIO | Realistic Input/Output Opportunity |