| Acronym | Definition |
|---|
| NSSI➣Non-Suicidal Self-Injury (intentional self damage) |
| NSSI➣National Social Security Institute (Bulgaria; pensions and benefits management) |
| NSSI➣National Security Space Institute (formerly the Air Force Space Operations School) |
| NSSI➣North Slope Science Initiative (Alaska) |
| NSSI➣Navrátil Software System Information |
| NSSI➣No Significant Schedule Impact |
| NSSI➣Nuclear Safety/Security Inspection |