- m Metre(s), SI unit of length (3.28084 feet).
- M or Mach number The ratio of the speed of a body to the speed of sound (340 m; 1,116 ft/s in air at 15°C) under the same ambient conditions.
- MAD Magnetic anomaly detector.
- mass balance Mass attached to flight control surface, typically ahead of hinge axis, internally or externally, to reduce or eliminate coupling with airframe flutter modes.
- mass flow Mass of air passing per second (usually at T-O, S/L).
- MAWS Missile-approach warning system.
- mb Millibar, bar x 10³.
- MCM Mine countermeasures.
- medevac Medical evacuation.
- MFD Multifunction (electronic) display.
- MHz Megahertz: 1 million (106) Hertz.
- microlight See ultralight.
- MIDS Multifunction information distribution system.
- MKR Marker beacon receiver.
- MLS Microwave landing system.
- MLU Mid-life update.
- MLW Maximum landing weight.
- mm Millimetres, metres x 10-3.
- MMO Maximum operating Mach number.
- MMS Mast-mounted sight.
- MoD Ministry of Defence.
- monocoque Structure with strength in outer shell, devoid of internal bracing (semi-monocoque, with some internal supporting structure).
- MoU Memorandum of Understanding.
- MPA Maritime patrol aircraft.
- mph Miles per hour.
- MSIP Multistaged improvement program (US).
- MTBF Mean time between failures.
- MTI Moving-target indication (radar).
- MTOW Maximum take-off weight (minus taxi/run-up fuel).
- MYP Multiyear procurement (US).
- MZFW Maximum zero-fuel weight.
