| Acronym | Definition |
|---|
| IOO➣In Our Opinion |
| IOO➣Independent Owner Operator (truck driver) |
| IOO➣Institut für Orgonforschung |
| IOO➣Idaho Operations Office |
| IOO➣Institut Ochrany Obyvatelstva (Czech: Institute of Protection of the Population; est. 1991) |
| IOO➣Internet Order Online (Poland) |