| Abbreviation | Definition |
|---|---|
| MARS | Militians At Ready Stance |
| MARS | Mitigation And Response System |
| MARVEL | Machine Assisted Realization of the Virtual Electronic Library |
| MAS | Mutually Assured Success |
| MASS | Multiline Accuracy Support System |
| MasterGunnerySergeant-Marines | MGySgt |
| MAT | Minimum Alternate Tax |
| MAUDE | Manufacturer and User Facility Device Experience |
| MBA | Made By America |
| MBA | Management By Accident |
| MBDA | Minority Business Development Agency |
| MBDC | Minority Business Development Council |
| MBE | Minority Business Enterprise |
| MBNMS | Monterey Bay National Marine Sanctuary |
| MBR | Medicine Bow- Routt National Forest |
| MC | Multiethic Community |
| MCA | Monitoring Curruption and Anticurruption |
| MCAPP | Mid- Continent Area Power Pool |
| MCC | Martinsburg Computer Center |
| MCC | Merchant Category Code |