- M – a prefix to the model number of a specific nomenclature of equipment, generally considered to denote "model" or "mark". Also us in the phonetic alphabet for "Mike".
- ma'am – proper method of addressing female officers in particular and all women in general.
- Mac Marine – nickname for Marine, popular during World War II, also the career planner popular on posters of the 1960s.
- mad max – term for a military vehicle that is irregular in appearance due to repairs, modifications or the presence of extra equipment. See also hillbilly armor.
- Maggie's drawers – red flag attached to a pole, used to signal a miss on the rifle range, replaced by a red disk.
- MAGTF – Marine Air-Ground Task Force.
- Major – a Captain in command of a ship's Marine detachment, so titled because a ship may have only one Captain, the commanding officer.
- Mama-san – term of endearment for an elder Japanese woman, often a maid, cook, or tailor/seamstress performing services for Marines; from the Japanese honorific suffix "san".
- MARINE – Muscles Are Required, Intelligence Non-Essential or My Ass Rides In Navy Equipment, pejorative backronyms used by other branches.
- Marine – the following nicknames are usually acceptable: leatherneck, devil dog, sea soldier, warrior, hard charger, motivator; the following are acceptable from other Marines: jarhead, gyrene; the following are insults: soldier, seabag.
- Marine house – Security Guard term for living quarters for Marines, on or off embassy grounds.
- Master Guns or Master Gunny – Master Gunnery Sergeant. Also sometimes referred to as "Maverick" due to the combination of slang for Master Sergeant "Top" and Gunnery Sergeant "Gunny".
- Marine Mattress – a woman who is thought to be sexually promiscuous with other Marines.
- MBT – Main Battle Tank, currently the M1 Abrams.
- MCI – Marine Corps Institute, a distance education program; also, the courses available to Marines for bonus promotion credit.
- MCCS – Marine Corps Community Services (also known by the humorous backronym Marine Corps Crime Syndicate)
- MCMAP, MCNinja – Marine Corps Martial Arts Program.
- MCT – Marine Combat Training, infantry skills training for non-infantry Marines.
- MCX – Marine Corps eXchange, a military department store, less formally known as the PX.
- meat gazer – urinalysis observer who observes the servicemember peeing into the sample container to prevent tampering with the sample.
- MEB – Marine Expeditionary Brigade.
- MEDEVAC or Medivac – MEDical EVACuation, removing a wounded person to the closest medical or triage facility using designated ambulance equipment, vehicles, or aircraft. See also CASEVAC.
- MEF – Marine Expeditionary Force.
- MEPS – Military Entrance Processing Station, facility where prospective recruits are screened medically, psychologically, and legally for recruit training.
- mess hall – cafeteria. See also chow hall.
- messman – cook.
- MEU – Marine Expeditionary Unit.
- MFWIC – Mother Fucker What's/Who's In Charge.
- Mickey Mouse boots – boots designed for extreme cold weather using an air bladder for insulation, so named for their oversized and bloated appearance.
- midrats – midnight (or other late-night) rations provided for servicemembers who work late hours.
- mike – minute.
- mike-mike – millimeter.
- military left – pertaining to the left side of something or the direction to the left of the subject in question. Used sarcastically when giving orders when a subordinate turns the wrong way or is unsure of which way to turn.
- military time – the time of day on a 24-hour clock. General Wallace M. Greene forbade the practice of suffixing the unnecessary word "hours" after each indication of time of day ("1330" or "thirteen-thirty" instead of "1330 hours"); the practice of saying "oh" instead of "zero" for hours before 1000 has diminished as well.
- MOLLE – MOdular Lightweight Load-carrying Equipment, type of load-bearing equipment utilizing the PALS, replaced ALICE and replaced by ILBE.
- Molly Marine – nickname associated with early female Marines, especially a statue of Opha Mae Johnson.
- monkey suit – military uniforms in general; originally, the fur suit used by aviators at high altitudes.
- moonbeam – flashlight.
- MOPP – Mission Oriented Protective Posture, the defense equipment (gas masks and overgarment suits) worn to protect against Nuclear, Biological, and Chemical weapons.
- mosquito wings or skeeter wings – rank insignia for a Private First Class, a single chevron.
- motivator – term of endearment from a senior to a junior Marine, so named when the junior displays motivation for his or her duties.
- moto – motivated/motivating, often used to describe a person, object, or event that would motivate an individual Marine.
- motarded – displaying excess motivation, often in the form of visual symbols and lore (such as unit logos); a combination of the terms "moto" and "retarded".
- motor t or MT – Motor Transport, a subunit of Marines responsible for the operation and maintenance of wheeled non-combat and non-engineer vehicles.
- MOUT – Military Operation in Urban Terrain. See also CQB/CQC.
- MOS – Military Occupational Specialty, a job classification.
- MP – Military Police, mostly replaced by PMO.
- MRE – Meal, Ready-to-Eat, standard U.S. field ration. Sometimes jokingly referred to with backronyms such as "Meals Rejected by the Enemy," "Meals Rejected by Ethiopia," "Meal, Rotten to Eject," "Meals Rarely Eaten," "Meal, Reluctant to Exit," "Mister E," or the "Three Lies for the Price of One".
- MRE bomb – bursting plastic bag made from chemical heating pouches found inside of a standard MRE.
- MSG – Marine Corps Security Guard, responsible for guarding United States Embassies.
- MTO – Motor Transport Officer, the Marine in charge of maintenance and operation of a unit's trucks.
- MTV – Modular Tactical Vest, the newest type of ballistic vest for Marines.
- MTVR – Medium Tactical Vehicle Replacement See also 7-ton.
- MWD – Military Working Dog, a trained government canine for law enforcement, detection of explosives and/or drugs, sentry, or other military use(s).
Read more about this topic: List Of United States Marine Corps Acronyms And Expressions