| Acronym | Definition |
|---|
| NNI | National Nanotechnology Initiative |
| NNI | Net National Income (economics) |
| NNI | Nanaimo (Amtrak station code; Nanaimo, British Columbia, Canada) |
| NNI | Nortel Networks, Inc. (Ontario, Canada) |
| NNI | Network-to-Network Interface |
| NNI | Native Numerical Interface |
| NNI | Network to Network Interface |
| NNI | Network to Network Implementation |
| NNI | Network Node Interface |
| NNI | No New Information |
| NNI | Network Node Interface (SS7 SCCP) |
| NNI | Nederlands Normalisatie-Instituut |
| NNI | National Neuroscience Institute (Singapore) |
| NNI | No Net Increase (emission standard; various locations) |
| NNI | Nikkei Net Interactive (Japan) |
| NNI | Newport News Industrial |
| NNI | New Networks Institute |
| NNI | Norman Noble, Inc. (Cleveland, OH) |
| NNI | Nearest Neighbour Interchange |
| NNI | Nehalem New Instructions (computing protocol) |
| NNI | Network Ninja, Inc. |
| NNI | Nonnuclear Instrumentation |
| NNI | Numéro National d'Identité (French: National Identity Number; France) |
| NNI | Neural Network Interface |
| NNI | Office of Naval Intelligence Publications (US Navy) |
| NNI | Non-Sustainable Non-Supportable & Obsolete Items |
| NNI | Notice of Non-Issue (insurance) |
| NNI | New Net Investment |