| Welsh baby names begining from S |
| Sadwm |
 | Welsh form of Saturn 'god of the harvest'. |
| Saer |
| Carpenter. |
| Saeth |
 | Arrow. |
| Saffir |
| Sapphire. |
| Saith |
| Seven. |
| Sarff |
| Snake. |
| Sayer |
| Carpenter. |
| Sayers |
| Carpenter. |
| Sayre |
| Carpenter. |
| Sayres |
| Carpenter. |
| Seith |
| Seven. |
| Sel |
| Legendary son of Selgi. |
| Selwyn |
| Ardour; fair. |
| Selyf |
| Welsh form of Solomon 'peace'. |
| Selyv |
| Legendary son of Kynan. |
| Seren |
| Star. |
| Sian |
| Welsh form of Jane: God is gracious. God's gift. |
| Siarl |
| Welsh form of Charles 'manly'. |
| Siawn |
| Legendary son of Iaen. |
| Siencyn |
| Welsh form of Jenkin 'God is gracious'. |
| Sinnoch |
| Legendary son of Seithved. |
| Sion |
 | Welsh form of John 'God is gracious'. |
| Sioned |
| Welsh form of Jane: God is gracious. God's gift. |
| Sior |
| Welsh form of George 'farmer'. |
| Steffan |
| Crown; wreath. Variant of Stephen. |
| Steffen |
| Crown; wreath. Variant of Stephen. |
| Steffon |
| Crown; wreath. Variant of Stephen. |
| Sugyn |
| Legendary son of Sugynedydd. |
| Sulyen |
| Legendary son of Iaen. |
| Syvwkh |
| Legendary son of Cleddyv KyvwIch. |
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