| M | Mega | - | Business and Finance |
| M | Mach | - | Business and Finance |
| M | Milli | - | Business and Finance |
| M&O | Maintenance And Operations | - | Business and Finance |
| M&S | Materials And Services | - | Business and Finance |
| M&V | Magnetism & Volcanoes | - | Business and Finance |
| M&V | Magmatism & Volcanoes | - | Business and Finance |
| M-ANL | Argonne National Laboratory | - | Business and Finance |
| M-BNW | Batelle Northwest | - | Business and Finance |
| M-ISWS | Illinois State Water Survey | - | Business and Finance |
| M-PDU | Multiplexed Protocol Data Unit | - | Business and Finance |
| M-SRI | Stanford Resource Institute | - | Business and Finance |
| M-UCSD | University Of California At San Diego | - | Business and Finance |
| M3 | M Cubed | - | Business and Finance |
| MAB | Man And The Biosphere Program | - | Business and Finance |
| MAB | Meteorological Applications Branch | - | Business and Finance |
| MAC | Machine Aided Cognition | - | Business and Finance |
| MAC | Multiple Access Computer | - | Business and Finance |
| MAC | Manager's Advisory Council | - | Business and Finance |
| MAC | Apple Macintosh Computer | - | Business and Finance |
| MAC | Medium Access Control | - | Business and Finance |
| MACCM2 | Middle Atmosphere Community Climate Model | - | Business and Finance |
| MACCM3 | Middle Atmosphere Community Climate Model | - | Business and Finance |
| MACRAT | Middle-Atmosphere Chemistry | - | Business and Finance |
| MADAM | Master Data Acquisition Module | - | Business and Finance |
| MADER | Management Of Atmospheric Data For Evaluation And Research | - | Business and Finance |
| MADIS | Meteorological Assimilation Data Ingest System | - | Business and Finance |
| MAF | Mesoscale Analysis Forecasting | - | Business and Finance |
| MAG | Magnetosphere Currents/Fields | - | Business and Finance |
| MAGE | Marine Aerosol And Gas Exchange Experiment | - | Business and Finance |
| MAGE | Marine Gas Emissions | - | Business and Finance |
| MAGSAT | Magnetic Field Satellite | - | Business and Finance |
| MALTS | Marine Layer Thickness Study | - | Business and Finance |
| MAMOS | Marine Automatic Meteorological Observing Station | - | Business and Finance |
| MAMS | Multispectral Atmospheric Mapping Sensor | - | Business and Finance |
| MAN | Metropolitan Area Network | - | Business and Finance |
| MAP | Mesoscale Alpine Project | - | Business and Finance |
| MAP | Metro-Agro-Plex | - | Business and Finance |
| MAP | Middle Atmosphere Program | - | Business and Finance |
| MAPCON | A Routine Developed By Unidata For Contouring NPS Gridded Data On A Background Map From NetCDF Files | - | Business and Finance |
| MAPR | Multi-angle Profiling Radar | - | Business and Finance |
| MAPS | Measurement Of Air Pollution From Satellites | - | Business and Finance |
| MAPS | Multiple Aircraft Positioning System | - | Business and Finance |
| MAPS | Mesoscale Analysis And Prediction System | - | Business and Finance |
| MAPS | Millions Of Actions Per Second | - | Business and Finance |
| MAPS/RUC | MAPS Is The Research Version Of The Rapid Update Cycle | - | Business and Finance |
| MAR | Modernization And Associated Restructing | - | Business and Finance |
| MAR | Marshall Field Site | - | Business and Finance |
| MARC | Middle Atmosphere Responses To Changes | - | Business and Finance |
| MARC | Machine Readable Cataloging | - | Business and Finance |
| MARD | Modernization Associated Restructuring Demonstration | - | Business and Finance |
| MARI | Middle Atmosphere Research Initiative | - | Business and Finance |
| MARK-IVB | N/A | - | Business and Finance |
| MARS | Meteorological Airborne Radar Data System | - | Business and Finance |
| MAS | Millimeter-wave Atmospheric Sounder | - | Business and Finance |
| MASDIS | Meteorological Assimilation Data Ingest System | - | Business and Finance |
| MASER | Microwave Amplification By Stimulated Emission Of Radiation | - | Business and Finance |
| MASI | Middle Atmosphere Science Initiative | - | Business and Finance |
| MASNET | Mainframe And Server Network | - | Business and Finance |
| MASP | Multi-angle Aerosol Spectrometer Probe | - | Business and Finance |
| MASSCOMP | Massachusetts Computer Corporation | - | Business and Finance |
| MATCH | Model For Atmospheric Chemistry And Transport | - | Business and Finance |
| MATCH | McGill University; Technical Improvements To The Large-scale Spectral Element Ocean Model (SEOM) | - | Business and Finance |
| MATEX | Massive Air Tracer Experiment | - | Business and Finance |
| MATR | MOPITT Algorithm Test Radiometer | - | Business and Finance |
| MAYPOLE | May Polarization Experiment | - | Business and Finance |
| MB | Millibar | - | Business and Finance |
| MB | Megabits | - | Business and Finance |
| MB | Megabytes | - | Business and Finance |
| MB | Millibar | - | Business and Finance |
| MBA | MB Associates | - | Business and Finance |
| MBO | Management By Objective | - | Business and Finance |
| MBONE | Multicast BackBONE | - | Business and Finance |
| MBPS | Megabits | - | Business and Finance |
| MBT | Miscellaneous Budget Transactions | - | Business and Finance |
| MBY | Megabyte | - | Business and Finance |
| MBYTE | Megabyte | - | Business and Finance |
| MCA | Moist Convective Adjustment | - | Business and Finance |
| MCA | Moist Convective Adjustment | - | Business and Finance |
| MCA | Micro Channel Architecture | - | Business and Finance |
| MCA | Manufacturing Chemists Association | - | Business and Finance |
| MCBE | McIDAS Broadcast Evaluation | - | Business and Finance |
| MCC | Mesoscale Convective Complex | - | Business and Finance |
| MCC | Mission Control Center | - | Business and Finance |
| MCCS | Mesoscale Convective Complexes | - | Business and Finance |
| MCIDAS | Man-computer Interactive Data Access System | - | Business and Finance |
| MCR | Multichannel Cloud Radiometer | - | Business and Finance |
| MCS | Mesoscale Convective System | - | Business and Finance |
| MCTEX | Maritime Continent Thunderstorm Experiment | - | Business and Finance |
| MCV | Mesoscale Cyclonic Vortex | - | Business and Finance |
| MD | Master Directory | - | Business and Finance |
| MD | Modernization Division | - | Business and Finance |
| MD FILE | N/A | - | Business and Finance |
| MDC | Modified Direct Costs | - | Business and Finance |
| MDCRS | Meteorological Data Collection And Reporting System | - | Business and Finance |
| MDDS | Maintenance Decision Support System | - | Business and Finance |
| MDI | Michelson Doppler Imager | - | Business and Finance |
| MDM | Multiplexer/demultiplexer | - | Business and Finance |
| MDR | Manually Digitized Radar | - | Business and Finance |
| MDS | Minimum Detectable Signal | - | Business and Finance |
