| Acronym | Definition |
|---|
| NIO➣Nicaragua Córdoba (ISO currency code) |
| NIO➣Northern Ireland Office |
| NIO➣National Institute of Oceanography |
| NIO➣Nickel Oxide (chemical compound) |
| NIO➣Nicht in Ordnung (German: Not in Order; production) |
| NIO➣New Input Output |
| NIO➣Non-Blocking Input Output |
| NIO➣National Intelligence Officer |
| NIO➣Nuveen Insured Municipal Opportunity Fund Inc. (Nuveen Investments) |
| NIO➣New Input/Output |
| NIO➣Neurotechnology Industry Organization (San Francisco, CA) |
| NIO➣Nickelore Limited (Australia) |
| NIO➣Northern Illawarra Online (Australia) |
| NIO➣Native Input Output |
| NIO➣Network Input Output |
| NIO➣Nioki, Zaire (airport code) |
| NIO➣Naval Inspector of Ordnance |
| NIO➣Navigational Information Office (US Navy) |
| NIO➣Network for Intercultural Onomastics (name etymology and naming practices) |
| NIO➣Network Information Operation |
| NIO➣Netzwerk Interferenz-Onomastik (German: Network Interference-Onomastics; name etymology and naming practices) |
| NIO➣Not in Office (political designation) |