| Abbreviation | Definition |
|---|---|
| MJ | Martin John |
| MJ | Marvel Junior |
| MJ | Marvin Jubilee |
| MJ | Mary Jane |
| MJ | Mary Jayne |
| MJ | Mary Jean |
| MJ | Mary Jeanne |
| MJ | Matthew James |
| MJ | Matthew Johnson |
| MJ | Matthew Justin |
| MJ | Max Junior |
| MJ | Melanie Joy |
| MJ | Mellisa Joy |
| MJ | Meridith Johnson |
| MJ | Michael James |
| MJ | Michael Jason |
| MJ | Michael John |
| MJ | Michael Joseph |
| MJ | Middle Joy |
| MJ | Midnight Junior |