| Acronym | Definition |
|---|
| OEI | Organización de Estados Iberoamericanos (Spanish) |
| OEI | One Engine Inoperative |
| OEI | Open Enterprise Infrastructure |
| OEI | Original Equipment Industries |
| OEI | Office of Evaluation and Inspections (US DHHS) |
| OEI | Office of Environmental Information |
| OEI | Office of Energy Independence (various locations) |
| OEI | Outside Equity Interest |
| OEI | Omron Electronics, Inc. (various locations) |
| OEI | Organizational Environment for Integration (Capability Maturity Model Integration) |
| OEI | Open Ended Investigation |
| OEI | Operational Efficiency Initiative (various organizations) |
| OEI | One Eye Integration (trauma therapy) |
| OEI | Operations Excellence Infusion |
| OEI | Office of Export Information |
| OEI | Ovarian Epithelial Inclusion |
| OEI | Ocean Exploitation Institute (fictitious organization; Terror of MechaGodzilla; 1975) |