M Mega- (medida métrica 10^6)
m meter(s)
m Milli (milésimo) (medida métrica 1/1000)
M Miniatures
MA Massachusetts (designação postal para estado americano)
MAAP Maintenance And Administration Panel
MAC an MIT interdepartmental lab (padrão para muitas coisas) (renomeado para LCS)
MAC Media Access Control
MAC Medium Access Control
MAC Military Air Command
MACSYMA project MAC's SYmbolic MAnipulation System
MAD Mutual Assured Destruction
MADD Mothers Against Drunk Driving
MAG Magazine
MAN Metropolitan Area Network
MAP Manufacturing Automation Protocol
MAP/TOP Manufacturing Automation Protocol/Technical Office Protocol
MARBI MAchine Readable form of Bibliographic Information
MARC MAchine Readable card Catalog
MARS Multiuser Archival and Retrieval System
MASC Multiple Award Schedule Contract
MASER Microwave Amplification by Stimulated Emission of Radiation
MASH Mobile Army Surgical Hospital
MAST Multi-Application SOnar Trainer
MAT-CALS Marine Air Traffic-Control And Landing System
MAU Math Acceleration Unit
MAU Media Access Unit
MAU Medium Access Unit
MB Manned Base (Espacial)
MB MegaByte
MBA Master Business Administration
MBTA Massachusetts Bay Transportation Authority
MC Master of Ceremonies
MCA Micro Channel Architecture
MCAE Mechanical Computer Aided Engineering
MCC Master Control Console
MCC Microelectronics and Computer technology Corporation
MCC Mission Control Center (Espacial)
MCP Master Control Program
MCP/AS Master Control Program/Advanced System
MCPO Master Chief Petty Officer
MCSV Mars Crew Sortie Vehicle [NASA OEXP]
MD Doctor of Medicine
MD Maryland
MD Maryland (designação postal para estado americano)
MD Medical Doctor
MD Months after Date
MDAS Magnetic Drum Auxiliary Sender
MDC Metropolitan District Commision (Agência estatal)
MDE Modular Design Environment
MDF Main Distribution Frame (Telefonia)
MDRE Mass Driver Reaction Engine (Espacial)
MDT Mean Down Time
ME Maine
ME Mechanical Engineer
MECO Main Engine CutOff (Espaço)
MEd Master of EDucation
MERP Middle-Earth Role Playing
MeV Million Electron Volts
MF Medium Frequency (300-3000KHz)
MF Middle French
MF Multi-Frequency (Telefonia)
MFA Master Fine Arts
MFA Museum of Fine Arts [Boston]
MFJ Modified Final Judgment (Telefonia)
MFLOPS Million FLoating-point OPerations per Second (veja também FLOPS)
MFM Modified Frequency Modulation
MFS Macintosh File System
MG Machine Gun
MG Major General
MG Military Government
MGH Massachusetts General Hospital
MGM Metro-Goldwyn Mayer (nome de companhia)
MHD MagnetoHydroDynamics
MHS Mail Handling System [ISO]
MHz Mega HertZ (unidade de freqüência, 1,000,000 ciclos por segundo)
MI Michigan
MI Military Intelligence
MIA Missing In Action
MIB Management Information Base
MIDI Musical Instrument Digital Interface
MIFASS Marine Integrated Fire And Support System
MILNET MILitary NETwork
MIM Morality In Media
MIMD Multiple Instruction, Multiple Data
MINCE MINCE Is Not Complete Emacs
MINE MINE Is Not Emacs 
MIPS Million Instructions Per Second
Mir Peace [Russian]
MIRV Multiple Independently-Targetable Reentry Vehicle
MIS Management Information System
MIT Massachusetts Institute of Technology
ML Middle Latin
mL milliliter(s)
MLA Member of Legislative Assembly (veja também MPP)
MLD Minimum Lethal Dose
MLL Mars Logistics Lander [NASA OEXP]
MLS Microwave Landing System
MLS Multi-Level Security
MLV Medium Lift Vehicle [NASA OEXP]
MM Maryknoll Missioners
mm millimeters
MMES Martin Marietta Energy Systems
MMFS Manufacturing Message Format Standard
MMH MonoMethyl Hydrazine (Espacial)
MMM see 3M
MMT Multiple Mirror Telescope (Espacial)
MMU Manned Maneuvering Unit (Espacial)
MMU Memory Management Unit
MMW Multi-Mega Watt (Espacial)
MN Minnesota
MNA Member of National Assembly (Quebec)
MNP Microcom Networking Protocol (nome de companhia)
MNRAS Monthly Notices of the Royal Astronomical Society (Espacial)
MO Mail Order
MO Medical Officer
MO Missouri
MO Modus Operandi
MO Money Order
MOC Mars Observer Camera (em Observador de Marte) (Espacial)
MOD Ministry of Defence (UK) (às vezes written MoD)
MOL Manned Orbiting Laboratory (Espacial)
MOLA Mars Observer Laser Altimeter (em Observador de Marte) (Espacial)
MOMA Museum of Modern Art [New York]
MOMV Manned Orbital Maneuvering Vehicle (Espacial)
MOR Middle-Of-the-Road
MOS Metal Oxide Semiconductor
MOSFET Metal Oxide Semiconductor Field Effect Transistor
MOTAS Member Of The Appropriate Sex
MOTIS Member Of The Inappropriate Sex
MOTIS Message-Oriented Text Interchange System
MOTOS Member of the Opposite Sex
MOTSS Member of the Same Sex
MOTV Manned Orbital Transfer Vehicle (Espacial)
MOU Memorandum Of Understanding
MOUSE Minimum Orbital Unmanned Satellite of Earth
MP Melting Point
MP Member of Parliament
MP Metropolitan Police
MP Military Police(man)
MPC Minor Planets Circular (Espacial)
MPE Mission to Planet Earth (Espacial)
MPG Miles Per Gallon
MPH Miles Per Hour
MPP Member of Provincial Parliament (Canada; também MLA)
MPR Mars Pressurized Rover (Espacial)
MPV Mars Piloted Vehicle [NASA OEXP]
MPW Macintosh Programmer's Workshop
MR Miniatures Rules
MRI Magnetic Resonance Imaging
MRP Manufacturing Requirements Planning
MRSR Mars Rover and Sample Return (Espacial)
MRSRM Mars Rover and Sample Return Mission (Espacial)
MS ManuScript
MS Master of Science
MS Military Science
MS Motor Ship
MS Multiple Sclerosis
MSB Most Significant Bit; Most Significant Byte
MSC MicroSoft C
MSCP Mass Storage Control Protocol
MSD Most Significant Digit
MS-DOS MicroSoft DOS
MSE Mobile Subscriber Equipment
MSFC (George C.) Marshall Space Flight Center (NASA) (Espacial)
MSFC Marshall Space Flight Center
MSG MonoSodium Glutamate
MSH Marvel Super Heroes
MSL Mean Sea Level
MSPCA Massachussetts Society for the Prevention of Cruelty to Animals
MSPE Mercenaries, Spies & Private Eyes
MSRP Manufacturer's Suggested Retail Price
MSS Management Support System
MSS ManuScriptS
MSS Mass Storage System
MSS Maximum Segment Size [TCP/IP] (veja também MTU)
MST Mountain Standard Time
MT Metric Ton
MT Mountain Time
MTA Message Transfer Agent
MTA Metropolitan Transportation Authority
MTBF Mean Time Between Failures
MTC Man Tended Capability (Espacial)
MTR Magnetic Tape Recording
MTSO Mobile Telephone Switching Office (Telefonia)
MTTF Mean Time To Failure
MTTR Mean Time To Recovery
MTTR Mean Time To Repair
MTU Maximum Transfer Unit (Networking) (veja também MSS)
MTV Music TeleVision
MUF Maximum Usable Frequency (Máxima freqüência durante a atividade)
MULTICS MULTiplex Information Computer Services
MUMPS Mgh Utility MultiProgram System
MUNG Mung Until No Good 
MUX MUltipleXor
MVA MegaVolt Ampere
MVS Multiple Virtual Storage [IBM]
MX Missile eXperimental
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