| MSSR | Magnetically Super Shielded Room 
| Others |
| MSSR | Marine Safety Specialist Response
| Others |
| MSSR | Marine Saftey Specialist Response
| Others |
| MSSR | Marine Scout Sniper Rifle
| Others |
| MSSR | Maritime Security Sector Reform
| Others |
| MSSR | Mars Surface Sample Return
| Others |
| MSSR | Maximum Safe Surface Residue
| Others |
| MSSR | McCormick Schmicks Seafood Restaurant
| Others |
| MSSR | Medical Students For Social Responsibility
| Others |
| MSSR | Mess Management Specialist Seaman Recruit
| Others |
| MSSR | Micro-Scale Social Restriction
| Others |
| MSSR | Minimum Sole Survivors Rate
| Others |
| MSSR | Mintonye Southwestern Summer Recreation
| Others |
| MSSR | Moderated School Self Review
| Others |
| MSSR | Moldavian Soviet Socialist Republic
| Others |
| MSSR | Moldovan Soviet Socialist Republic
| Others |
| MSSR | Molecular Screening Shared Resource
| Others |
| MSSR | Monopulse Secondary Surveilance Radar
| Others |
| MSSR | Monopulse Secondary Surveillance Radar
| Others |
| MSSR | Monterey Summer Symposium on Russia
| Others |
| MSSR | Morphine Sulfate Sustained Release
| Others |
| MSSR | Multi Service Switch Router
| Others |
| MSSR | Multi Start Space Reduction
| Others |
| MSSR | Mustang Special Service Registry
| Others |