| Abbreviation | Definition |
|---|---|
| MS | Mid South |
| MSA | Maryland State Archives |
| MSA | Minnesota State Aid |
| MSB | Marginal Social Benefit |
| MSBA | Metropolitan Suburban Bus Authority |
| MSBC | Mississippi State Board of Cosmetology |
| MSBE | Ministry of Small Business and Entrepreneurship |
| MSBI | Minnesota State Board of Investment |
| MSCBA | Massachusetts State College Building Authority |
| MSCN | Minnesota Sustainable Communities Network |
| MSCQ | Medical Society of the County of Queens |
| MSDA | Maryland State Dental Association |
| MSEA | Michigan State Employees Association |
| MSEC | Massachusetts Sports Entertainment Commission |
| MSEC | Montana State Employers Council |
| MSFC | Metropolitan Sports Facilities Commission |
| MSH | Mount St. Helens |
| MSP | Medicaid State Plan |
| MSSC | Montana Safety Services Council |
| MSTC | Mississippi State Tax Commission |