| Abbreviation | Definition |
|---|---|
| MR | Morningstar Rating |
| MRC | Media Resource Center |
| MRC | Michigan Radio Cluster |
| MRP | Most Recent Printing |
| MRQ | Medical Review Quarterly |
| MRRG | Mississippi River Radio Group |
| MRS | Media Recogintion System |
| MRS | Most Requested Show |
| MRS | Music Recording Service |
| MRT | Migration Review Tribunal |
| MRW | My reaction when |
| MRZ | Mutant Renegade Zine |
| MS | Maple Story |
| MS | Math-Science Quest for Solutions |
| MS | Movie Star |
| MS | Movie Stills |
| MSA | Magic Shadow Archive |
| MSA | Metallus Sonic Adventure |
| MSA | Metropolitan Service Area |
| MSCG | Mike Sty Computer Guy - newspaper columnist |