| # | Name | Origin | Meaning | Gender | |
|---|---|---|---|---|---|
| 1421 | Moreen | Irish | Great. | F | |
| 1422 | Morella | Irish | Great. | F | |
| 1423 | Morgan | Irish | Fighter of the sea. | M | |
| 1424 | Morgayne | Irish | Medieval form of Welsh Morcan, meaning bright sea. | F | |
| 1425 | Moriarty | Irish | Expert seaman. | M | |
| 1426 | Morna | Irish | Beloved. | F | |
| 1427 | Morrin | Irish | Long haired. | F | |
| 1428 | Morrissey | Irish | Choice of the sea. | M | |
| 1429 | Moya | Irish | Bitter. | F | |
| 1430 | Moyna | Irish | Variant of Mona: Noble. | F | |
| 1431 | Muadhnait | Irish | Noble one. | F | |
| 1432 | Muiel | Irish | Knows the sea. | F | |
| 1433 | Muircheartaigh | Irish | Expert seaman. | M | |
| 1434 | Muire | Irish | Bitter. | F | |
| 1435 | Muireadhach | Irish | Lord of the sea. | M | |
| 1436 | Muireann | Irish | Long haired. | F | |
| 1437 | Muirgheal | Irish | Knows the sea. | F | |
| 1438 | Muirne | Irish | Beloved. | F | |
| 1439 | Mukonry | Irish | Hound of prosperity. | M | |
| 1440 | Mulcahy | Irish | Battle chief. | M | |