| M | Messier | - | Atmospheric Research Center |
| M | Mach | - | Organizations |
| M | Maintainability | - | Organizations |
| M | Major Cycle | - | Organizations |
| M | Male | - | Organizations |
| M | Mandatory | - | Organizations |
| M | Manual | - | Organizations |
| M | Mass | - | Organizations |
| M | Matrix | - | Organizations |
| M | Mega | - | Organizations |
| M | Mercury | - | Organizations |
| M | Meter | - | Organizations |
| M | Middle | - | Organizations |
| M | Million | - | Organizations |
| M | Missing (Data) | - | Organizations |
| M | Monitor (MON Preferred) | - | Organizations |
| M | Number Of Revolutions Required For The Rendezvous | - | Organizations |
| M | Isc Miscel Laneous | - | Organizations |
| M | LGS Microwave Landing Guidance System | - | Organizations |
| M | Lss Mission | - | Organizations |
| M | LAMDM Launch Aft | - | Organizations |
| M | LAMonochrome Lens Assembly | - | Organizations |
| M | PSS Main Parachute Support Structure | - | Organizations |
| M | B/SMegabits Per Second | - | Organizations |
| M | BACMarshall Booster Assembly Contractor | - | Organizations |
| M | DSDMate/Demate Stiffleg Derrick | - | Organizations |
| M | ECCA Master Electrical Common Connector Assembly | - | Organizations |
| M | ESAMiniature Electrostatic Accelerometer | - | Organizations |
| M | ESAModular Equipment Stowage Assembly | - | Organizations |
| M | Icom Missile Command (Army) | - | Organizations |
| M | ITTSE Mobile Lgor Tracking Telescope System | - | Organizations |
| M | LcsManagement Information And Control System | - | Organizations |
| M | PTPMain Propulsion Test Program | - | Organizations |
| M | PTSMultipurpose Tool Set | - | Organizations |
| M | Meter(s) | - | Scuba Diving |
| M | Male | - | Sms Text Smileys and Emoticons |
| M | Mega - One Thousand (in Roman Numerals) | - | Astronomy |
| M | Metre - Milli | - | Astronomy |
| M | Mega | - | Business and Finance |
| M | Mach | - | Business and Finance |
| M | Milli | - | Business and Finance |
