| Abbreviation | Definition |
|---|---|
| m | married,male, mother |
| M | Mother |
| M. | Married |
| m2 | second marriage |
| m3 | third marriage |
| MD | Married |
| mgfa | maternal grandfather |
| MGM | Maternal GrandMother |
| mgmo | maternal grandmother |
| MGP | Mathematics Genealogy Project |
| MIHCK | Myosin I Heavy Chain Kinase |
| MIY | married in that year |
| Mo | Mother |
| Mo. | Mother |
| MPSGG | Muskoka, Parry Sound Genealogy Group |
| MSOG | Massachusetts Society Of Genealogy |
| MTGS | Middle Tennessee Genealogical Society |
| n.d. | no date |
| n/a | not available, not applicable, unknown |
| N/A | Not Available, unknown |