| Siaghal | A leader of noble character. |
| Sibilini | Name of a Mountain |
| Sioda | As soft as fine woven silk. |
| Siofra | Precocious Child, A Changing |
| Siomonn | One who listens with intent. |
| Siomun | A name meaning he has heard. |
| Siothrun | A name meaning wise protector. |
| Siridean | Searcher; Peaceful |
| Sitric | A name meaning victory of peace. |
| Slane | Homestead of Fullness |
| Slawin | Man of Mountain |
| Slebine | A name meaning mountain dweller. |
| Sleibhin | A name meaning little mountain. |
| Solamh | A name meaning man of peace. |
| Solav | A name meaning sun of the earth. |
| Spann | Name for a Quarrelsome |
| Steefan | Garland; Crowned |
| Steimhin | A name meaning a royal crown. |
| Stiabhna | A name meaning a noble garland. |
| Stiana | Crowned; Garland |
| Stibhin | A name meaning a victors crown. |
| Strachan | From the valley of the stream. |
| Suibhne | Well Going; Pleasant; Friendly |
| Suibne | Friendly; Well Going; Pleasant |
| Suileabhain | Small; Dark Eye |
| Saadiqoon | Honest, truthful, and sincere |
| Sadih | Gentle, kind, and compassionate |
| Safiful | Pious, devout, and God-fearing |
| Sahabir | Wise, intelligent, and knowledgeable |
| Sahalam | Generous, charitable, and benevolent |
| Sahibul | Owner, master, or ruler |
| Sahnwaz | Brave; God's Gift |
| Saiyab | Beautiful, lovely, and charming |
| Sajvan | Intelligent, wise, and discerning |
| Sakhib | Friend, companion, or associate |
| Sakkeer | Intelligent, wise, and knowledgeable |
| Sanoof | Beautiful, lovely, and charming |
| Saquelain | Intelligent, wise, and discerning |
| Sarfaz | Brave, courageous, and strong |
| Sebu | Intelligent, wise, and knowledgeable |