| Celtic boys baby names begining from A |
| Adair |
 | From the ford by the oak trees. |
| Aengus |
 | Exceptionally strong. |
| Ahearn |
 | Lord of the horses. |
| Ahern |
 | Lord of the horses. |
| Aidan |
 | Fire. |
| Aiden |
 | Fire. |
| Ailill |
 | Mythical king of Connaught. |
| Airell |
 | Nobleman. |
| Al |
 | 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. |
| Alain |
 | Variant 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. |
| 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. See also Allen. |
| Alanson |
 | Son of Allan. |
| Albion |
 | White cliffs. Ancient poetic name for Britain. |
| Allan |
 | 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. See also Allen. |
| Allen |
 | 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. |
| Allie |
 | 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. |
| Ally |
 | 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. |
| Allyn |
 | Handsome. |
| Alun |
 | 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. |
| Anant |
 | From the stream. |
| Anghus |
 | Exceptionally strong. |
| Angus |
 | Exceptionally strong. |
| Annan |
 | From the stream. |
| Ansgar |
 | Warrior. |
| Anwell |
 | Beloved. |
| Anwyl |
 | Beloved. |
| Anyon |
 | Anvil. |
| Aod |
 | Mythical son of Lyr. |
| Aodh |
 | Fire. |
| Aodhan |
 | Fire. |
| Aonghus |
 | Exceptionally strong. |
| Ap Owen |
 | Son of Owen. |
| Arawn |
 | Mythical king of the Underworld. |
| Arden |
 | Eager; ardent. |
| Argyle |
 | From the land of the Irish. |
| Arlan |
 | Oath. |
| Arlen |
 | Oath. |
| Arlin |
 | Oath. |
| Arlyn |
 | Oath. |
| Art |
 | Strong as a bear. |
| Artair |
 | Variant of Arthur: Bear; rock. |
| Arte |
 | Diminutive of Arthur: Bear; rock. |
| Artek |
 | Variant of Arthur: Bear; rock. |
| Arthur |
 | Strong as a bear. |
| Artie |
 | Diminutive of Arthur: Bear; rock. |
| Artis |
 | Diminutive of Arthur: Bear; rock. |
| Arto |
 | Diminutive of Arthur: Bear; rock. |
| Artur |
 | Strong as a bear. |
| Arturo |
 | Strong as a bear. |
| Arty |
 | Diminutive of Arthur: Bear; rock. |
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