| Acronym | Meaning |
| MSFC | Marshall Space Flight Center |
| MSFIA | Multisyringe Flow Injection Analysispar |
| MSG | Monosodium Glutamate |
| MSGC | Microstrip Gas Chamber |
| MSH | Melanocyte-stimulating Hormone |
| MSHA | Mine Safety And Health Administration (US) |
| MSI | Microsatellite Instability |
| MSIA | Mass Spectrometric Immunoassay |
| MSIP | Magnetron Sputtering Ion Plating |
| MSIS | Mass Spectrometer And Incoherent Scatter |
| MSK | Muscular-skeletal Effects |
| MSL | Mean Sea Level |
| MSM | Multiple-scattering Model |
| MSM | Multishell Method |
| MSMA | Murrell-Shaw-Musher-Amos Exchange Perturbation Theory |
| MSMO | Multiple Scattering Molecular Orbital Method (also Known As X(alpha) Scattered-wave) |
| MSMPR | Mixed-solution-mixed-product Removal |
| MSO | Maximum Similarity (spin) Orbital |
| MSO | Modified Slater Orbital |
| MSO | Molecular Spin Orbital |
| MSP | Macrophage Stimulating Protein |
| MSP | Manganese Stabilizing Protein |
| MSP | Merozoite Surface Protein |
| MSP | Monosodium Phosphate |
| MSPC | Multivariate Statistical Process Control |
| MSPD | Matrix Solid-Phase Dispersion |
| MSPO | Method Of Successive P |
| MSPR | Molecular Structure-property Relationship |
| MSR | Mammalian Selectivity Ratio |
| MSRI | Mass Spectroscopy Of Recoiled Ions |
| MSS | Mobile Servicing Station [space Station] |
| MSS | Monosulfide Solid Solution |
| MSS | Multispectral Scanner |
| MSSA | Methicillin-susceptible Staphylococcus Aureus |
| MSSM | Minimal Supersymmetric Standard Model |
| MST | Microbial Source Tracking |
| MST | Mean Survival Time |
| MST | Multiple Scattering Theory |
| MSUD | Maple Syrup Urine Disease |
| MSV | Morse-Spline-van Der Waals (interatomic Potential) |
| MSW | Municipal Solid Waste |
| MSW-X(ALPHA) | Multiple Scattered Wave-SCF-x(alpha) |
| MSWI | Municipal Solid Waste Incinerator(s) |
| MSWLF | Municipal Solid Waste Landfill |
| MSWV | Multiple Square Wave Voltammetry |
| MSX | Midcourse Space Experiment |
| MSZ | Magnesia-stabilized Zirconia |
| MTAB | Myristyltrimethylammonium Bromide (surfactant) |
| MTB | Mycobacterium Tuberculosis |
| MTBE | Methyl Tert Butyl Ether (gasoline Additive) |