| Abbreviation | Definition |
|---|---|
| MBSA | Midwest Building Suppliers Association |
| MC | McCoy |
| MD | Microdot |
| ME | Mepco |
| MH | Mechanical Products |
| MHSA | Mental Health Services Act |
| MI | Millipore |
| MK | Merrimac |
| ML | Malco |
| MM | Microsemi |
| MO | Marco |
| MoE | Ministry of Electricity (Iraq) |
| MP | Micropac |
| MR | Motorola |
| MRV | Most Reliable Vendor |
| MS | Micro-Switch |
| MT | Matrix |
| MW | McCormack Williamson |
| MY | Mallory |
| NE | Nippon Electric |