| Abbreviation | Definition |
|---|---|
| SSMS | Single Shelter Message Switch |
| SSN | Attack Submarine, Nuclear |
| SSN | Nuclear-powered Attack Submarine (Submarine, Submarine, Nuclear) |
| SSN | Social Security Number |
| SSN | Space Surveillance Network |
| SSN | Standard Study Number |
| SSN | Sub Surface Nuclear |
| SSN | System Study Number |
| SS-N-2 | Scrubber Missile |
| SS-N-2 | Styx Missile |
| SS-N-20 | Sturgeon Missile |
| SS-N-3A | haddock Missile |
| SS-N-3A | Shaddock Missile |
| SS-N-5 | Sark Missile |
| SS-N-6 | Serb Missile |
| SS-N-8 | Sawfly Missile |
| SS-N-9 | Siren Missile |
| SSNA | Shan State National Army |
| SS-NX-23 | Skiff Missile |
| SSO | Signal Security Office |