| Acronym | Meaning |
| MAG | Myelin-associated Glycoprotein |
| MAGE | Melanoma-associated Antigen-encoding Gene |
| MAGE | Marine Aerosol And Gas Exchange Experiment |
| MAGE | MicroArray And Gene Expression |
| MAGIC | Major Atmospheric Gamma Imaging Cherenkov |
| MAGIC | Model Of Acidification Of Groundwater In Catchments |
| MAGIC | Monodisperse Aerosol Generation Interface For Combining Liquid Chromatography With Mass Spectrometry |
| MAGICC | Model For The Assessment Of Greenhouse-gas Induced Climate Change |
| MAGW | Momentum-averaged Gaussian-weighted (method In Calcns. Of Electron-momentum Distributions) |
| MAH | Magic-angle Hopping |
| MAHRSI | Middle Atmosphere High Resolution Spectrograph Investigation |
| MAIDS | Murine Acquired Immunodeficiency Syndrome |
| MAK | Maximale Arbeitplatz Konzentration; Maximum Allowed Concentration At Workplace |
| MALDI | Matrix-Assisted Laser Desorption Ionization |
| MALLS | Multiple-angle Laser Light Scattering |
| MALS | Multi-angle Light Scattering |
| MALT | Mucosa-associated Lymphoid Tissue |
| MAM | Modified Atoms (in) Molecules |
| MAMA | Multianode Microchannel Arrays |
| MAMBO | Mars Atm. Microwave Brightness Observer |
| MAMO | Multiparameter Alternant Molecular Orbital |
| MAMS | Multispectral Atmospheric Mapping Sensor |
| MAMU | Mobile (ambient) Air Monitoring Unit (Canada) |
| MANCOVA | Multivariate Analysis Of Covariance |
| MAO | Methyl Aluminoxanes |
| MAO | Modified Atomic Orbital |
| MAO | Monoamine Oxidase |
| MAOI | Monoamine Oxidase Inhibitor |
| MAOP | Maximum Allowable Operating Pressure |
| MAOS | Microwave-assisted Organic Synthesis |
| MAOSS | Magic Angle Oriented Sample Spinning |
| MAOT | Maximum Allowable Operating Temperature For Stationary Phase |
| MAP | Magnesium Ammonium Phosphate |
| MAP | Mean Arterial Pressure |
| MAP | Microtubule-associated Protein |
| MAP | Mitogen Activated Protein |
| MAP | Modified Atmosphere Packaging |
| MAP2 | Microtubule-associated Protein 2 |
| MAP3S | Multi-State Atmospheric Power Production Pollution Study |
| MAPK | Mitogen-activated Protein Kinase |
| MAPKK | Mitogen-activated Protein Kinase Kinase |
| MAPLE | Madelung Part Of Lattice Energy |
| MAPLE | Matrix-assisted Pulsed Laser Evaporation |
| MAPS | Measurement Of Air Pollution From Satellites |
| MAPTAC | Acrylamide-N |
| MAPW | Modified Augmented Plane Wave |
| MAR | Matrix Attachment Region |
| MARB | Methanotropic Air-tight Rotating Bioreactor |
| MARCKS | Myristoylated Alanine-rich C Kinase Substrate |
| MARDIGRAS | Matrix Analysis Of Relaxation For DIscerning The Geometry Of An Aqueous Structure |