| Acronym | Definition |
|---|
| ONI | Office of Naval Intelligence |
| ONI | Office of Neighborhood Involvement (various locations) |
| ONI | OpenNet Initiative (Internet filtering and surveillance research) |
| ONI | Optical Network Infrastructure |
| ONI | Office National d'Immigration (French: National Immigration Office) |
| ONI | Operator Number Identification |
| ONI | Okayama Network, Inc. (Okayama, Japan) |
| ONI | Oncology News International (journal) |
| ONI | Orientación do Nuevos Integrantes (Spanish: New Members Orientation) |
| ONI | Outside Network Interface (telephony) |
| ONI | Ormat Nevada Inc. (energy firm) |
| ONI | Office of NWTS Integration |