| NSIA | National Security and Intelligence Agency 
| Others |
| NSIA | National Security and International Affairs
| Others |
| NSIA | National Security Industrial Association
| Others |
| NSIA | National Security Internet Archive
| Others |
| NSIA | National Society Investment Alliance
| Others |
| NSIA | National Sport Inclusion Alliance
| Others |
| NSIA | National Statistic and Information Authority
| Others |
| NSIA | National Study of Intercollegiate Athletics
| Others |
| NSIA | Nebraska Self Insurers Association
| Others |
| NSIA | Nebraska Society of Independent Accountants
| Others |
| NSIA | Nebraska State Irrigation Association
| Others |
| NSIA | Network Security and Information Assurance
| Others |
| NSIA | Nevada Self Insurers Association
| Others |
| NSIA | Nigeria Sovereign Investment Authority
| Others |
| NSIA | Nigerian Sovereign Investment Authority
| Others |
| NSIA | North Seattle Industrial Association
| Others |
| NSIA | North Shore Ice Arena
| Others |
| NSIA | North Shore International Academy
| Others |
| NSIA | North Shore International Academy North Shore International Academy
| Others |
| NSIA | Northwest Sportfishing Industry Association
| Others |
| NSIA | Nova Scotia Institute of Agrologists
| Others |
| NSIA | Noxious Stimulus Induced Analgesia
| Others |
| NSIA | Noxious Stimulus Induced Antinociception
| Others |