| Acronym | Definition |
|---|
| NI | No Information |
| NI | National Instruments |
| NI | Northern Ireland |
| NI | No Idea |
| NI | National Insurance |
| NI | Norfolk Island |
| NI | Nigeria |
| NI | Nickel |
| NI | Not Important |
| NI | Nicaragua (ISO country code, top level domain) |
| NI | Not Interested |
| NI | Net Income |
| NI | North Island (New Zealand) |
| NI | Network Interface |
| NI | Needs Improvement |
| NI | Negative Impact |
| NI | Nueva Izquierda (Spanish: New Left) |
| NI | Natural Ingredients |
| NI | National Income |
| NI | National Identification (number; US DoD) |
| NI | Nosocomial Infection |
| NI | Net Investment |
| NI | Naval Intelligence |
| NI | Neurological Institute |
| NI | Portugalia Airlines (IATA airline code) |
| NI | National ISDN (Integrated Services Digital Network) |
| NI | Noted Item (US DoD) |
| NI | Navistar International (trucks and tractors) |
| NI | Network Implementation |
| NI | Nutrition Institute |
| NI | Nickel Institute |
| NI | Not Insulated |
| NI | Network Industry (frequent in company description of the new economy) |
| NI | New Institutionalism (EU) |
| NI | Nuclear Instrumentation |
| NI | Nex Imperio (gaming alliance) |
| NI | Network Indicator |
| NI | Networld + Interop |
| NI | Named Insured (insurance) |
| NI | Nanotechnology Institute (American Society of Mechanical Engineers) |
| NI | Noise Intensity |
| NI | Nationella Insatsstyrkan (Swedish equivalent of SWAT police force) |
| NI | Neonatal Isoerythrolysis (hemolytic disease of foals) |
| NI | Navigation and Interaction (software engineering) |
| NI | Number of Invocations |
| NI | Natural Interference |
| NI | Northwood Institute (Midland, Michigan) |
| NI | Natione Itala (Latin: Italic Nation, epigraphy) |
| NI | Neoist International (governing body of Art/Agitprop conferees) |