| Acronym | Definition |
|---|
| IU | Indiana University |
| IU | Izquierda Unida (United Left, Spain) |
| IU | Intermediate Unit |
| IU | International Unit |
| IU | Izquierda Unida (United Left, Bolivia) |
| IU | Intrauterine |
| IU | In Utero |
| IU | Instrument Unit (US NASA) |
| IU | Iowa University |
| IU | International University in Germany |
| IU | Image Understanding |
| IU | Immaculata University (Immaculata, PA) |
| IU | Impuesto Único (Spanish: Single Tax; Chile) |
| IU | Industrial User |
| IU | Imaging Unit |
| IU | Interface Unit |
| IU | Integer Unit (CPU) |
| IU | Istanbul University |
| IU | International Undertaking on Plant Genetic Resources (est. 1983; UN Food and Agriculture Organization) |
| IU | Independent Union |
| IU | Inch Up (elevators) |
| IU | Iwate University (Morioka, Iwate, Japan) |
| IU | Immunizing Unit |
| IU | Intelligent Unit |
| IU | Interrogation Unit |
| IU | Interaction Unit |
| IU | Idiot User |
| IU | Interrupt Unit |
| IU | Icon Ultima (game) |
| IU | Intel University |
| IU | Individualais Uznemums (Latvian: Personal Company - Analog Company) |