| Name | Meaning | Gender | Origin |
|---|
| Smokey | A grayish blue colour. Slang for highway patrol officer | Unisex | English |
| Snickers | A brand of candy bar. | Unisex | English |
| Snowball | | Unisex | Hebrew |
| Snowflake | Single flake or crystal of snow. | Unisex | English |
| Solo | | Unisex | Hebrew |
| Spanky | | Unisex | Hebrew |
| Sparky | Animated, lively. | Unisex | English |
| Spaz | For a spazy kitty | Unisex | English |
| Speckles | | Unisex | Hebrew |
| Spidey | | Unisex | Hebrew |
| Spirit | Part of the human being associated with the mind. Vigorous or animated state - spirited. Also distilled alcohol. | Unisex | English |
| Spooky | | Unisex | Hebrew |
| Spot | After Data's cat on Star Trek: The Next Generation | Unisex | English |
| Sprinkles | | Unisex | Hebrew |
| Sprite | Lemonade flavored soft drink. | Unisex | English |
| Spunky | Spirited, plucky. | Unisex | English |
| Squeaky | | Unisex | Hebrew |
| Squishy | | Unisex | Hebrew |
| Stardust | | Unisex | Hebrew |
| Starlight | | Unisex | Hebrew |
| Stimpy | | Unisex | Hebrew |
| Stinker | | Unisex | Hebrew |
| Stinkie | | Unisex | Hebrew |
| Stinky | | Unisex | Hebrew |
| Stitch | After the character in the Lilo And Stitch cartoon | Unisex | English |
| Stormy | Violent weather | Unisex | English |
| Suede | Swedish | Unisex | English |
| Taboo | | Unisex | Hebrew |
| Tac | | Unisex | Hebrew |
| Taco | A folded fried tortilla filled with meat, cheese and spices. | Unisex | English |