| Acronym | Definition |
|---|
| NAI | North American Indian (language) |
| NAI | NASA Astrobiology Institute |
| NAI | Network Access Identifier (Wireless IP Network Architecture) |
| NAI | Netherlands Architecture Institute |
| NaI | Sodium Iodide |
| NAI | Network Associates, Inc. |
| NAI | Network Advertising Initiative |
| NAI | Nordic Africa Institute |
| NAI | New and Improved |
| NAI | No Action Indicated (US FDA) |
| NAI | National Aerospace Initiative |
| NAI | No Adverse Impact (flood mitigation) |
| NAI | New America International |
| NAI | Nachrichten Aus Israel |
| NAI | Notifiable Avian Influenza (surveillance system) |
| NAI | Named Area of Interest |
| NAI | Nature of Address Indicator (SS7 SCCP) |
| NAI | National Associates, Inc. |
| NAI | Nürnberger Altersinventar |
| NAI | Northwest Avalanche Institute |
| NAI | Network Application Integration |
| NAI | Nacelle Anti-Ice (aviation) |
| NAI | Neutral Atom Imager |
| NAI | Nuclear Accident or Incident |
| NAI | NATO Analog Interface (connects NATO analog signal equipment to the MSE/DGM network) |
| NAI | Nic Augustus Investigations (Baltimore, MD) |
| NAI | Naval Ammunition Interchangeability |
| NAI | North American Inks |
| NAI | Number of Active Ingredients (pharmaceutical industry) |
| NAI | National Account Index |
| NAI | Network Applications Incorporated |
| NAI | Network Access Index |
| NAI | Neuraminidase Activity Inhibition |
| NAI | Network Application Installer |
| NAI | Navy Action Item |
| NAI | No Airborne Intercept |
| NAI | Nigerian Association Ireland (est. 2005) |
| NAI | Numerof and Associates, Inc. (Saint Louis, MO) |
| NAI | No Advice Intended |