| Abbreviation | Definition |
|---|---|
| MG | Mark George |
| MG | Mary Grace |
| MG | Mathew Gilbert |
| MG | Mickey's Girl |
| MG | Mikhail Gregory |
| MG | Morris George |
| MGA | My Giddy Aunt |
| MGGM | Maternal Great Grandmother |
| MGK | Machine Gun Kelley |
| MIKE | Michael |
| Mila | Milena |
| MIMI | Miriam |
| MITCH | Mitchell |
| MJ | Mamma Jamma |
| MJ | Margaret Jane |
| MJ | Margo Jill |
| MJ | Maria Jane |
| MJ | Maria Jose |
| MJ | Martha Jean |
| MJ | Martin Jarvis |