| Machinist's Mate | |
|---|---|
 Rating insignia | |
| Issued by | United States Navy |
| Type | Enlisted rating |
| Abbreviation | MM |
| Specialty | Engineering / Weapons |
Machinist's Mate (or MM) is a rating in the United States Navy's engineering community. It is non-capitalised as machinist's mate when discussing the generic rating rather than as a proper noun when discussing a specific enlisted seaman (Machinist's Mate Jane Doe, MM John Doe) carrying that rating.