| # | Name | Origin | Meaning | Gender | |
|---|---|---|---|---|---|
| 1 | Adair | Celtic | From the ford by the oak trees. | M | |
| 2 | Aengus | Celtic | Exceptionally strong. | M | |
| 3 | Afric | Celtic | Agreeable. | F | |
| 4 | Africa | Celtic | Agreeable. | F | |
| 5 | Ahearn | Celtic | Lord of the horses. | M | |
| 6 | Ahern | Celtic | Lord of the horses. | M | |
| 7 | Aidan | Celtic | Fire. | M | |
| 8 | Aiden | Celtic | Fire. | M | |
| 9 | Aife | Celtic | A great warrior woman of myth. | F | |
| 10 | Aigneis | Celtic | Pure. | F | |
| 11 | Ailidh | Celtic | Kind. | F | |
| 12 | Ailill | Celtic | Mythical king of Connaught. | M | |
| 13 | Ailis | Celtic | Noble. | F | |
| 14 | Aina | Celtic | Joy. | F | |
| 15 | Aine | Celtic | Fire or joy. | F | |
| 16 | Aingeal | Celtic | Angel. | F | |
| 17 | Airell | Celtic | Nobleman. | M | |
| 18 | Airic | Celtic | Agreeable. | F | |
| 19 | Aithne | Celtic | Fire. | F | |
| 20 | Al | Celtic | Diminutive of Alan: Harmony, stone, or noble. Also fair, handsome. Originally a saint's name, it was reintroduced to Britain during the Norman Conquest, remained popular throughout the Middle Ages, and was revived in the 19th century. | M | |