| Name | Gender | Meaning | Favorites |
| Siddhi | Girl | Achievement, Ever ready to protect, Goddess, Lord Shiva | |
| Siddhran | Boy | Perfection | |
| Siddiq | Boy | A true friend, Just, One who is true in word and deed, Sincere | |
| Siddiqah | Girl | One who keeps her word | |
| Sidhak | Boy | Faith | |
| Sidhesh | Boy | Lord of the blessed | |
| Sidonie | Girl | Flower | |
| Sidra | Girl | Of the stars | |
| Sienna | Girl | Reddish brown | |
| Sigmund | Boy | Victorious protector | |
| Sihaam | Girl | Arrows | |
| Siham | Girl | Arrows | |
| Sikander | Boy | A great king | |
| Silaah | Boy | Armour, Arms, Weapons | |
| Silambarasan | Boy | The best | |
| Silvanos | Boy | Forest Dweller | |
| Silver | Boy, Girl | White | |
| Silverio | Boy | Greek god of trees | |
| Silvester | Boy | Forest Dweller | |
| Silvia | Girl | Of the woods | |
