| Acronym | Definition |
|---|
| OPI | Other (Political) Party Identifier |
| OPI | Office of Public Instruction |
| OPI | Oral Proficiency Interview (English language test) |
| OPI | Office of Police Integrity (Victoria, Australia) |
| OPI | Office Products International (London, UK) |
| OPI | Oracle Program Interface |
| OPI | Office of Public Information |
| OPI | Open Prepress Interface |
| OPI | Office of Primary Interest |
| OPI | Operator Interface |
| OPI | Outsource Partners International, Inc. |
| OPI | Over the Phone Interpretation (Language Line Services, Monterey, CA) |
| OPI | Oxygen Percentage Indicator (Respironics) |
| OPI | Omnitel Pronto Italia |
| OPI | Ontario Petroleum Institute (Canada) |
| OPI | Openings Per Inch ( air filter mesh grades) |
| OPI | Omnibus Personality Inventory |
| OPI | Operational Performance Indicator |
| OPI | Odontorium Products, Inc. (North Hollywood, CA) |
| OPI | Optional Procedure Indicator |
| OPI | Outdoor Pointing Interface (meter for aligning broadband satellite signals for internet) |
| OPI | Optus Private IP |
| OPI | Outside Plant Interface |
| OPI | Open Payment Initiative |
| OPI | Oil Pressure In |
| OPI | Old Patient In |
| OPI | Obscenity, Profanity, Indecency (FCC) |
| OPI | Ocean Profile on the Internet |
| OPI | Office of Policy Integration (DOE) |
| OPI | Organizational Performance Infrastructure |
| OPI | Other People's Inventory |
| OPI | Oxaloacetate Pyruvate Insulin |
| OPI | Operator's Instructions |
| OPI | Object of Potential Interest (robotics) |
| OPI | Other People's Incompetence |
| OPI | Orthopedic Precision Instruments (Indiana) |
| OPI | Oil Plant Institute (Vietnam) |
| OPI | Organizational Performance Improvement (Association of American Medical Colleges) |
| OPI | Oremus Pro Invicem (Latin: Let Us Pray for Each Other) |
| OPI | Orphan Pharma international (est. 1999) |