| Acronym | Definition |
|---|
| S4➣Secondary 4 (various locations) |
| S4➣Supply Officer (Army) |
| S4➣Sleep Mode 4 (hibernation computer sleep mode) |
| S4➣Stainless Sanitary Space System |
| S4➣Logistics/Embark Office (USMC) |
| S4➣Supersonicsoundscapes (event promotions/record store) |
| S4➣NATO SG/2 Shareable (Fire Control) Software Suite |