| Secure copy | Secure copy |
| Secure internet live conferencing | SILC |
| Secure Real-time Transport Protocol | Secure Real-time Transport Protocol |
| Secure shell file system | SSHFS |
| Securitas AB | Securitas AB |
| Securitate | Securitate |
| Securities and Exchange Commission | United States Securities and Exchange Commission |
| Security Account Manager | Security Accounts Manager |
| Security assertion markup language | SAML |
| Security Intelligence Service | New Zealand Security Intelligence Service |
| Seddon | Seddon |
| Sedecias | Zedekiah |
| Sedelsberg | Sedelsberg |
| Sedgefield | Sedgefield |
| Sedia gestatoria | Sedia gestatoria |
| Sedna | Sedna |
| Sedov | Sedov |
| Seeberg | Seeberg |
| Seegräben | Seegräben |
| Seeing | Astronomical seeing |
| Seeland | Zealand |
| Seelisberg | Seelisberg |
| Seelow | Seelow |
| Seelze | Seelze |
| Seengen | Seengen |
| seersucker | seersucker |
| Seesen | Seesen |
| Seewald | Seewald |
| Seewen | Seewen |
| Seewis im Prättigau | Seewis im Prättigau |
| Sefer Avot | Mishnah Tractate Avot |
| Sefer Berakhot | Mishnah Tractate Berakhot |
| Sefer Ha Zohar | Zohar |
| Sefer Halilović | Sefer Halilović |
| Sefer Torah | Sefer Torah |
| Sefer Yetsirah | Yetzirah |
| Sefid Roud | Sefid River |
| Seftigen | Seftigen |
| Sega | Sega |
| Sega Megadrive Collection | Sega Genesis Collection |
| Sega Naomi | Sega NAOMI |
| Sega Pico | Sega Pico |
| Sega Rally Championship | Sega Rally Championship |
| Sega Titan Video | ST-V |
| Segata Sanshiro | Segata Sanshiro |
| Segestriidae | Tube-dwelling spider |
| Segisaurus | Segisaurus |
| segment | segment |
| segment circulaire | circular segment |
| Segment de données | Data segment |
| segment de piston | piston ring |
| Segment de population | Market segment |
| segmentation | segmentation |
| Segmentation stratégique | Market segment |
| segmenter | segment |
