| # | Name | Origin | Meaning | Gender | |
|---|---|---|---|---|---|
| 1661 | Siany | Irish | Good health. | F | |
| 1662 | Sibeal | Irish | Prophetess. | F | |
| 1663 | Sierra | Irish | Dark. Feminine of Ciaran. | F | |
| 1664 | Sile | Irish | Youthful. | F | |
| 1665 | Sine | Irish | Praise. | F | |
| 1666 | Sinead | Irish | Gaelic form of Jane: God is gracious. Famous Bearer: singer Sinead O'Connor. | F | |
| 1667 | Sineidin | Irish | Praise. | F | |
| 1668 | Siobhan | Irish | Praise. Famous Bearer: actress Siobhan McKenna. | F | |
| 1669 | Siodhachan | Irish | Little peaceful one. | M | |
| 1670 | Sive | Irish | Good. | F | |
| 1671 | Slaine | Irish | Good health. | F | |
| 1672 | Slany | Irish | Good health. | F | |
| 1673 | Sorcha | Irish | Bright; intelligent. | F | |
| 1674 | Sorley | Irish | Viking. | M | |
| 1675 | Sosanna | Irish | Lily. | F | |
| 1676 | Sruthair | Irish | From the stream. | M | |
| 1677 | Sruthan | Irish | Poet. | M | |
| 1678 | Strahan | Irish | Poet. | M | |
| 1679 | Struthers | Irish | From the stream. | M | |
| 1680 | Suidhne | Irish | Little hero. | M | |