| Acronym | Meaning |
| MAREMF | MARtian Electrons And Magnetic Field |
| MARF | Magic Angle In The Rotating Frame |
| MARG | Microarray Research Group |
| MARIA | Methods For Assessing The Radiological Impact Of Accidents |
| MARIS | Mississippi Automated Resource Information System |
| MARISS | Mass Resolved Ion Scattering Spectrometry |
| MARK | Mid-Atlantic Ridge At The Kane Fracture Zone |
| MARS | Membrane Anaerobic Reactor System |
| MARS | Multivariate Adaptive Regression Splines |
| MARY | Magnetic Field Effect On The Reaction Yield |
| MAS | Magic Angle Spinning (solid State NMR) |
| MAS | Molecular Absorption Spectroscopy |
| MASE | Microwave-assisted Solvent Extraction |
| MASER | Microwave Amplification By Stimulated Emission Of Radiation |
| MASERATI | Middle Atmosphere Spectrometric Experiment On Rockets For Analysis Of Trace Gas Influences |
| MASH | MgO-Al2O3-SiO2-H2O System |
| MASIF | Measurement And Analysis Of Surface Interaction Forces |
| MASP-HMO | Mutual Additive Substituent Parameter-Hueckel Molecular Orbital |
| MASS | Magic Angle Sample Spinning |
| MAST | Marine Science And Technology Programme |
| MAST | Mega-Amp Spherical Tokamak |
| MASTER | Method Of Adhesion By Spin-on-dielectric Temperature Enhanced Reflow |
| MAT | Magic Angle Turning |
| MAT | Microactivity Tests |
| MATC | Maximum Acceptable Toxicant Concentrations |
| MATHEW | Mass-Consistent-3-Dimensional Wind Field |
| MATI | Mass-analyzed Threshold Ionization Spectroscopy |
| MAVRIQ | Model Of Analysis Of Volatiles And Residential Indoor-air Quality |
| MAWP | Maximum Allowable Working Pressure |
| MAXI | Monitor Of All-sky X-ray Image |
| MB-SAPT | Many Body-symmetry Adapted Perturbation Theory |
| MB-SAPT | Many-body Symmetry-adapted Perturbation Theory |
| MBAS | Methylene Blue Active Substance (surfactant) |
| MBBR | Moving Bed Biofilm Reactor |
| MBE | Many-body Expansion (in Mol. Potential Energy Surface Calcn.) |
| MBE | Molecular Beam Epitaxy |
| MBER | Molecular Beam Electron Resonance |
| MBESHO | Maximum Bond-energy Symmetry Hybrid Orbital |
| MBESMO | Maximum Bond Energy Symmetry MO |
| MBESO | Maximum Bond Energy Symmetry Orbital |
| MBGF | Many-body Green Function |
| MBH | Mediobasal Hypothalamus |
| MBIE | Mixed-bed Ion Exchange |
| MBMS | Molecular Beam Mass Spectrometry |
| MBP | Major Basic Protein |
| MBP | Maltose-binding Protein |
| MBP | Mixed Basis Pseudopotential (method For Electronic-structure) |
| MBP | Myelin Basic Protein |
| MBPLS | Multiblock Partial Least Squares |
| MBPM | Maximum Bubble Pressure Method |