| Acronym | Meaning |
| MNDOD | Modified Neglect Of Diatomic Overlap With D At. Orbitals |
| MNOS | Metal-nitride Oxide Semiconductor |
| MNSR | Miniature Neutron Source Reactor |
| MNT | Molecular Nanotechnology |
| MO | Molecular Orbital |
| MOA | Maximum Overlap Approximation |
| MOAG | MINDO Optimized Adjusted Geometries |
| MOBI | MO Bond Index |
| MOBK | Modified Oppenheimer-Brinkman-Kramers (approxn. In Calcns. On Atomic And Molecular Collisions With Ions) |
| MOCD | Molecular Orbital Correlation Diagram |
| MOCE | Marine Optical Characterization Experiment |
| MOCED | Molecular Orbital Constrained Electron Diffraction Method |
| MOCETGAO | Molecule-optimized Contracted Even-tempered Gaussian Atomic Orbital |
| MOCIC | MO Constraint Of Interaction Coordinates |
| MOCVD | Metal Org. Chem. Vapor Deposition |
| MOD | Metalorganic Decomposition |
| MODESC | Magnetooptically Detected Spin Conversion Spectroscopy |
| MODFET | Modulation-doped Field-effect Transistor |
| MODIS | Moderate Resolution Imaging Spectroradiometer |
| MODPOT | Model Potential |
| MODR | Microwave Optical Double Resonance |
| MODS | Magneto-Optical Difference Spectroscopy |
| MODS | Multiple Organ Dysfunction Syndrome |
| MODULUS | Methods Of Determining And Understanding Light Elements From Unequivocal Stable Isotope Compositions |
| MODY | Maturity Onset Diabetes Of The Young |
| MOE | Margin Of Exposure |
| MOE | Modulus Of Elasticity |
| MOEMS | Micro-opto-electromechanical System |
| MOEXP | Morse Oscillator Exponential Repulsion Potential |
| MOF | Metal-organic Framework Compoundpar |
| MOFAT | Multi Phase Flow And Transport |
| MOFT | Minimum Oil Film Thickness |
| MOG | Mobil Olefins-to-gasoline [process] |
| MOG | Myelin Oligodendrocyte Glycoprotein |
| MOGA | Michigan Oil And Gas Association |
| MOI | Multiplicity Of Infection |
| MOKE | Magneto-optic Kerr Effect |
| MOLE | Molecular Optics Laser Examiner |
| MOLED | Molecular Organic Light Emitting Diode |
| MOLIERE (V5) | Microwave Observation LIne Estn. And Retrieval |
| MOLLI | Modular Luminescence Lifetime Imaging System |
| MOM | Maximum Overlap Method |
| MOM | Modified Operator Method (for Energy-level Calcns.) |
| MOMBE | Metal Organic Molecular-beam Epitaxy |
| MOMO | Maximum Overlap Molecular Orbital |
| MOMP | Major Outer Membrane Protein |
| MON | Motor (method) Octane No. |
| MONES | Molecular Nonthermal Excitation Spectrometry |
| MONOS | Metal Oxide Nitride Oxide Semiconductor |
| MOPA | Master Oscillator Power Amplifier |