| M | Mach (speed of sound in air at NTP) |
| mega (1 000 000 = 106) |
| m | Metre |
| milli (0.001 = 10-3) |
| M & E | Mechanical and electrical |
| M lat | Mean latitude (nav) |
| M2M | Machine-to-machine (communications) |
| MAC | Mean aerodynamic chord |
| Multiplexed analogue components (TV) |
| MACA | Maritime air control authority |
| MAD | Magnetic anomaly detector |
| Mutual assured destruction |
| MADGE | Microwave aircraft digital guidance system |
| MAG | Magnetised material (cargo) |
| mag | Magnetic |
| maint | Maintenance |
| MALS | Medium-intensity approach lighting system |
| MANPADS | Man-portable air defence system |
| manprint | Manpower and personnel integration |
| MAOT | Maximum allowable operation time |
| Mobile air operations team |
| MAP | Manufacturing automation protocol |
| marep | Maritime report |
| maridas | Maritime data system |
| marisat | Maritime satelite |
| Marpol | Marine Pollution Convention |
| MARS | Meteorological and aeronautical information services retrieval system |
| MART | Mean active repair time |
| MARV | Manoeuvrable re-entry vehicle |
| MAS | Middle air space |
| Military Agency for Standardization |
| Military area services |
| mat | Material |
| MATELO | Maritime Air Telecommunications Organisation |
| matl | Material |
| MATO | Military air traffic operations |
| MATS | Manual of air traffic services |
| MATV | Multi-axis thrust vectoring |
| MATZ | Military air traffic zone |
| MAWEC | Maritime exercise aircraft weather code |
| MAWS | Missile approach warning system |
| max | Maximum |
| MB | Munitions board |
| mb | Millibar (1 mb = 100 Pa = 0.750 mmHg) |
| mbar | Millibar (1 mbar = 100 Pa = 0.750 mmHg) |
| MBC | Military budget committee |
| MBE | Molecular beam epitaxy |
| MBFR | Mutual and balanced force reductions |
| MBS | Medium bomber strike |
| MBT | Main battle tank |
| MC | Machinery certificate |
| Military committee |
| MCC | Military control centre |
| Mission control centre |
| MCCIS | Military command, control and information system |
| MCDU | Multi-purpose control and display unit |
| MCM | Military committee memorandum |
| Mines countermeasures |
| Multi-chip module (electronics) |
| MCMV | Mines countermeasures vessel |
| MCP | Missile control point |
| Mode control panel |
| MCT | Mobile command team |
| MCVFT | Multi-carrier voice frequency telegraph |
| MCW | Modulated continuous wave |
| MDA | Minimum descent altitude |
| MDF | Main distribution frame (electric) |
| MDH | Minimum descent height |
| MDWT | Metric dead weight ton |
| ME | Main engine |
| MEA | Minimum en-route altitude |
| MEAS | Mission-essential avionics spares |
| med | Medical |
| Medium |
| medevac | Medical evacuation |
| MEF | Minimum-essential facility |
| MEG | Magneto-encephalography |
| mega | 1 000 000 = 106 |
| memo | Memorandum |
| MEMS | Micro electro-mechanical system |
| MEP | Mean effective pressure |
| mer alt | Meridian altitude (nav) |
| mer pass | Meridian passage (nav) |
| mercast | Merchant ship broadcast |
| MERMAID | Maritime environmental model and integrated database (oceanography) |
| MEROD | Message entry and read-out device |
| merzone | Merchant shipping control zone |
| MES | Mobile earth station (satellite) |
| MESAR | Multi-function electronically scanned adaptive radar |
| met | Meteorology |
| metar | Meteorological aerodrome report |
| MEWSG | Multiservice electronic warfare support group |
| MEXE | Military Engineering Experimental Establishment |
| MEZ | Missile engagement zone |
| MF | Medium frequency (300 kHz to 3 MHz) |
| MFC | Mortar fire controller |
| MFD | Multi-function display |
| MFDS | Multi-function display system (cockpit) |
| MFTD | Maintenance and flight training device |
| MFTS | Military flying training system |
| MG | Machine gun |
| MGID | Military geographic information and documentation |
| MHE | Materials-handling equipment |
| MHQ | Maritime headquarters |
| MHW | Mean high water |
| MHWS | Mean high water spring |
| MHz | Megahertz (1 000 000 Hz) |
| MICAS | Military intelligence combat aerial surveillance |
| MICR | Magnetic ink character recognition |
| MICV | Mechanised infantry combat vehicle |
| MID | Maritime identification digits |
| Minimum infective dose |
| MIDACS | Microprocessor data acquisition system |
| MIDAS | Missile defence alarm system |
| MIDI | Musical instrument digital interface |
| MIDS | Multifunctional information distribution system |
| Mig | Metal inert gas (welding) |
| MIJI | Meaconing, intrusion, jamming and interference |
| mil | Military |
| Mil-Std | Military standard (USA) |
| MILSM | Ministry of Defence Integrated Logistic Support Manager |
| MILSTRIP | Military standard requisitioning and issue procedure |
| MIMD | Multiple instruction, multiple data |
| min | Minimum |
| Minute |
| mips | Million instructions per second (computer) |
| MIR | Military infrastructure requirement |
| MIRV | Multiple independently targetable re-entry vehicle |
| MIS | Management information system |
| MISPEC | Merit of individual system performance characteristics |
| Mk | Mark |
| MKR | Marker radio beacon |
| ml | Millilitre (0.001 l = 1 cm3) |
| MLAT | Military logistic advisory team |
| MLC | Military load class |
| MLD | Median lethal dose |
| MLG | Main landing gear |
| MLLW | Mean low low water |
| MLRS | Multiple-launch rocket system |
| MLS | Microwave landing system |
| MLSAM | Ministry of Defence Logistic Support Analysis Manager |
| MLT | Mean life time |
| MLU | Mid-life update |
| MLV | Medium launch vehicle (USA) rocket |
| MLW | Mean low water |
| MLWS | Mean low water spring |
| MM | Mercantile marine |
| Middle marker |
| mm | Millimetre (0.001 m) |
| mm Hg | Millimetres of mercury (air pressure) |
| MMC | Metal matrix composite |
| MMG | Medium machine gun |
| MMH/FH | Maintenance man hours per flight hour |
| MMI | Man/machine interface (computer) |
| MMLC | Medium mobility load carrier |
| MMP | Maintenance monitor point |
| MMR | Minimum military requirement |
| MMS | Multi-media messaging system |
| MMSI | Maritime mobile selective identity (code) |
| MMU | Memory management unit |
| MMX | Multi-media extensions (computer) |
| MN | Merchant navy |
| MND | Mission need document |
| MNPS | Minimum navigation performance specification |
| MO | Medical officer |
| MOA | Memorandum of agreement |
| MOB | Main operating base |
| mob | Mobilisation |
| MOBS | Multiple orbital bombardment system |
| MOC | Message processing centre |
| MOCA | Minimum operational clearance altitude |
| MoD | Ministry of Defence |
| MoD (Air) | Ministry of Defence (Air) |
| MoD (Army) | Ministry of Defence (Army) |
| MoD (Navy) | Ministry of Defence (Navy) |
| modem | Modulator/demodulator (signal) |
| MODPM | Ministry of Defence project manager |
| MODS | Multiplexed optical data storage |
| MOE | Method of entry |
| mogas | Motor gasoline |
| MOH | Maximum operating hours |
| MOP | Military operations |
| Monitor panel |
| MOPS | Minimum operational performance standard |
| MOR | Magneto-optical recording |
| Military operational requirement |
| MOS | Machine operating system |
| Metal oxide semiconductor |
| Minimum operating strip (aircraft) |
| MOSFET | Metal-oxide semiconductor field-effect transistor |
| MOSS | Meteorological observation system for ships |
| MOTNE | Meteorological Operational Telecommunications Network Europe |
| MOU | Memorandum of understanding |
| MOUT | Military operations in urban terrain |
| MovO | Movement order |
| MP | Maritime patrol |
| Melting point |
| Meridional parts (nav) |
| Message processor |
| Military police |
| MPA | Maritime patrol aircraft |
| MPa | Megapascal (1 MN/m2) |
| MPD | Maintenance planning data |
| Maximum permissible dose |
| Multi-purpose display (avionics) |
| Multi-purpose dredger |
| MPE | Maximum permissible exposure |
| MPEG | Moving Picture Experts Group (ISO) |
| mph | Mile per hour (1.609 km/h or 0.868 knot) |
| MPI | Mean point of impact |
| MPU | Microprocessor unit |
| MPV | Mine protected vehicle |
| mpx | Multiplex |
| MRA | Miniature radar altimeter |
| Minimum reception altitude |
| MRAM | Magnetoresistive RAM |
| MRAV | Multi-role armoured vehicle |
| MRBM | Medium-range ballistic missile |
| MRC | Medical Research Council |
| MRCA | Multi-role combat aircraft |
| MRCC | Maritime rescue co-ordination centre |
| MRCS | Mobile reporting and control system |
| MRF | Multi-role fighter (aircraft) |
| MRFL | Master radio frequency list |
| MRI | Magnetic resonance imaging |
| MRL | Multiple rocket launcher |
| MRP | Manufacture recording process |
| MRPA | Machine-readable pronunciation alphabet |
| MRSA | Mandatory radar service area |
| MRSAM | Medium-range surface-to-air missile |
| MRT | Manoeuvre room trainer (Royal Navy) |
| MRV | Multiple re-entry vehicle |
| MS | Machinery survey |
| Mass spectrometer |
| Mild steel |
| Military standard |
| Motor ship |
| ms | millisecond (10-3 second) |
| MSA | Minimum safe altitude |
| MSAM | Medium-range surface-to-air missile |
| MSC | Major subordinate command |
| MSD | Minimum separation distance |
| MSDS | Mission-specific data set |
| MSI | Maritime safety information |
| Medium-scale integration |
| MSK | Minimum shift keying (telegraphy) |
| MSL | Mean sea level (nav) |
| MSOGS | Molecular sieve oxygen generating system |
| MSRC | Multi-carrier station remote control |
| MSSR | Monopulse secondary surveillance radar |
| MST | Microsystem technology |
| MSTAR | Man-portable surveillance and target acquisition radar |
| MT | Mechanical transport |
| Motor transport |
| Mt | Megaton (1 000 000 tons) |
| Mountain |
| MTA | Military training area |
| MTB | Motor torpedo boat |
| MTBD | Mean time between defects |
| MTBF | Mean time between failures |
| Multi-function bomb fuze |
| MTBM | Mean time between maintenance |
| MTBR | Mean time between repairs |
| MTBUR | Mean time between unscheduled removals |
| MTC | Marine traffic control |
| MTD | Moving target detection (radar) |
| MTDS | Maintenance, test and diagnostic section |
| MTF | Mean time to failure |
| MTI | Moving target indicator (radar) |
| MTL | Mean tidal level |
| MTM | Maintenance training manual |
| MTOW | Maximum take-off weight |
| MTR | Missile-tracking radar |
| MTS | Maintenance training simulator |
| MTTR | Mean time to repair |
| Mean time to restore |
| MTV | Maritime training vessel |
| MTWA | Maximum total weight authorised |
| mu | micro (10-6) |
| MUAT | Mobile underwater acoustic unit |
| MUCROS | Multi-computer operating system |
| MUF | Maximum usable frequency |
| mux | Multiplexer |
| MV | Medium voltage |
| Military vigilance |
| Motor vessel |
| Muzzle velocity |
| MVA | Million volt amperes |
| MVEE | Military Vehicles and Engineering Establishment |
| MW | Medium wave |
| Megawatt |
| Mine warfare |
| MWe | Megawatt electrical |
| MWHQ | Main War Headquarters |
| Mobile War Headquarters |
| MWS | Maritime Warfare School (Royal Navy) |
| MWTR | Mine warfare testing range |
| MZD | Meridian zenith distance (nav) |
