| Abbreviation | Definition |
|---|---|
| MOCC | Mazda Owners Club of California |
| MOFPS | Multiplayer Online First Person Shooter |
| MOMM | Miata Owners of Mid Michigan |
| MOTH | Memorable Order of Tin Hats |
| Moto | Motocross |
| MPCNC | Mostly Printed CNC |
| MQ | Museum Quality |
| MQR | Museum Quality Replica |
| MQX | Machine Quilter's Exposition |
| MQX | MQX Quilt Festivals Machine Quilters Exposition |
| MRA | Motorcycle Riders Association |
| MRC | Medieval Recreation Club |
| MRC | Milwaukee Repeater Club |
| MRCC | Modesto Radio Control Club |
| MRD | Mountain Riders Discipleship |
| MRHS | Maritime Radio Historical Society |
| MRoA | Merciless Riflemen of America |
| MRS | Model Railway Society |
| MS | Miniature Smooth |
| MSAA | Mower Specialists Association of Australia |