| Abbreviation | Definition |
|---|---|
| MC | Music Cards |
| MCAB | Masters Championship of Amateur Brewing |
| MCC | Macomb County Choppers |
| MCC | Motor Cycling Club |
| MCC | My Classic Car |
| MCC | Myott Collectors Club |
| MCDONALDS | Minute Cost Door Open All Nick Like Dad Sick |
| MCJ | Master Chef Junior |
| MCM | Motor City Murderers |
| MCO | Muscle Cars of Orlando |
| MCRC | Manatee County Radio Controllers |
| MCSA | Marble Collectors Society of America |
| MCSA | Mountain Club of South Africa |
| MCSCC | Midwestern Council Family of Sports Car Clubs |
| MCSCC | Motor City Stamp and Cover Club |
| MCTC | Mid-Cities Technical Club |
| MDBA | Museum Diablo Beekeepers Association |
| MDCA | Midwest Decoy Collectors Association |
| ME | Mazda Enthusiasts |
| MEA | Marklin Enthusiasts of America |