| Abbreviation | Definition |
|---|---|
| MRBA | Mount Rainier Business Association |
| MRCA | Missouri Rodeo Cowboys Association |
| MRDA | Manitoba Riding for the Disabled Association |
| MRDA | Mens Roller Derby Association |
| MRDA | Men's Roller Derby Association |
| MRDA | Missouri Rental Dealers Association |
| MREA | Michigan Rocket Engineering Association |
| MREA | Minnesota Rural Electric Association |
| MRHA | Maryland Rural Health Association |
| MRHA | Michigan Retail Hardware Association |
| MRHA | Midwest Ranch Horse Association |
| MRHA | Milwaukee Road Historical Association |
| MRHA | Mississippi Rural Health Association |
| MRHA | Missouri Reining Horse Association |
| MRHA | Missouri Rural Health Association |
| MRHA | Montana Reining Horse Association |
| MRHA | Montana Rural Health Association |
| MRIA | Marine Renewables Industry Association |
| MRIA | Marketing Research and Intelligence Association |
| MRIA | Marketing Research Intelligence Association |