| Abbreviation | Definition |
|---|---|
| MRHS | Mountain Range High School |
| MRHS | Mountain Ridge High School |
| MRHSA | Mainland Regional High School Alumni |
| MRSB | Montpelier Roxbury School Board |
| MRSD | Mainland Regional School District |
| MRSD | Manchester Regional School District |
| MRSD | Merced River School District |
| MRSD | Monadnock Regional School District |
| MRSD | Monmouth Regional School District |
| MRSS | Maple Ridge Secondary School |
| MRSS | Melbourne Rudolf Steiner School |
| MRU | Mill River Union High School |
| MS | Middle School |
| MS | Mountaineering School |
| MSA | Manatee School For the Arts |
| MSA | Metropolitan School Academy |
| MSA | Minnesota Math and Science Academy |
| MSAD | Maine School Administrative District |
| MSAE | Maharishi School of the Age of Enlightenment |
| MSAI | Multidimensional School Anger Inventory |