| Abbreviation | Definition |
|---|---|
| MCSA | Midwest Collegiate Ski and Snowboard Association |
| MCSA | Montgomery County Soccer Association |
| MCSE | Minesweeper Consultant and Solitaire Engineer |
| MCSSA | Madison County Shooting Sports Association |
| MCSSA | Montgomery County Senior Sports Association |
| MDBA | Minneapolis District Bowling Association |
| MDK | Maximally Daring Karate |
| MDQ | Match Disqualification |
| MDR | Maiden Dirt Route |
| MDR | Middle Distance Runner |
| MDR | Most Dangerous Receiver |
| MDRV | Mason-Dixon Roller Vixens |
| MdS | Marathon des Sables |
| MDSC | Metropolitan Detroit Ski Council |
| MDSO | Million Dollar Shoot-Out |
| ME | Mental Error |
| MEAC | Mid-Eastern Athletic Conference |
| MEB | Maintaining Excellent Balance |
| MEC | Missouri Equine Council |
| MEQ | Mid-East Qualifier |