| Acronym | Definition |
|---|
| IEO | Instituto Español de Oceanografía |
| IEO | In Excess Of |
| IEO | Institut d'Estudis Occitans (Catalan: Institute of Occitan Studies) |
| IEO | Istituto Europeo di Oncologia (Italy) |
| IEO | Independent Evaluation Office (IMF) |
| IEO | Interrupt Enable Output |
| IEO | International Exchange Office |
| IEO | Information Exploitation Office |
| IEO | Indian Environmental Office |
| IEO | Internal Evaluation Office |
| IEO | Integrated Electronic File |
| IEO | International Economic Organisation |
| IEO | Informal Eating Out (restaurant industry) |
| IEO | In Everyone's Opinion (slang) |
| IEO | Installation Environmental Office |
| IEO | Intermediate Earth Orbit |
| IEO | International English Olympiad (language exam) |