| Sofonisba | A noble Carthaginian princess. |
| Soh | Sine over hypotenuse in math. |
| Sojourner | One who stays for a short time. |
| Sokar | Ancient Egyptian god of the dead. |
| Solar | Relating to the sun or sunlight. |
| Soleia | A name meaning light or the sun. |
| Solene | Derived from the Latin word for solemn. |
| Soleus | A muscle located in the lower calf area. |
| Solfege | A method for teaching musical pitch. |
| Solivagant | One who wanders alone by themselves. |
| Solvi | A name meaning to loosen or release. |
| Sonaal | A name meaning golden or precious. |
| Sonata | A composition played on instruments. |
| Sop | A piece of bread dipped in liquid. |
| Sophos | A Greek term meaning wise or clever. |
| Sorbet | A frozen dessert made from fruit. |
| Soul | The spiritual essence of a person. |
| Spand | A variant of the word for expansion. |
| Speck | A tiny spot or a very small particle. |
| Speke | An archaic term meaning to speak out. |
| Spiti | A remote mountain valley in India. |
| Spock | A name meaning one from the meadow. |
| Srut | Derived from the Sanskrit for heard. |
| Staccato | Notes played in a detached manner. |
| Stag | A fully grown male adult deer animal. |
| Starfire | A brilliant light from the cosmos. |
| Starkad | A legendary Norse warrior hero. |
| Stassi | A Greek name meaning resurrection. |
| Staten | Derived from a Dutch word for state. |
| Static | Something fixed or lacking motion. |
| Stebin | A variant of the name Stephen. |
| Steelie | One who is strong like tempered iron. |
| Stellaluna | A name meaning star and moon. |
| Stellar | Relating to or resembling the stars. |
| Sthapatya | The ancient Indian art of building. |
| Stomp | To tread heavily with the feet. |
| Strum | To play a guitar by sweeping strings. |
| Strummer | One who plays a stringed instrument. |
| Struna | A word meaning string in Slavic tongues. |
| Strung | Having been fitted with tight strings. |