| Abbreviation | Definition |
|---|---|
| MR | McQuarrie's Rock |
| MRAC | Mining Regulations Advisory Committee |
| MRC | Maximum Reservoir Contact |
| MRF | Mineral Resources Forum |
| MRS | Mountain Research Station |
| MRSS | Malaysian Remote Sensing Society |
| MRV | Macal River Valley |
| MS | Martensite |
| MS | Mount Shasta |
| MSCA | Mobilized Soil Conductivity Assessment |
| MSCY | Mississippi Silty Clay Loam |
| MSDS | Mine Safety Determination Specification |
| MSE | Mars Soil Expose |
| MST | Modal Survey Test |
| MSTM | Mississippi Transverse Mercator |
| MTD | Measured Total Depth |
| MTGR | Mineral and Thermal Groundwater Resources |
| MTJ | Mendocino Triple Junction |
| MTNS | Mountains |
| MUFL | Main Urals Fault Line |