| Acronym | Meaning |
| MOPITT | Measurements Of Pollution In The Troposphere |
| MOPS | 3-(N-morpholino)propanesulfonic Acid |
| MOPW | Modified Orthogonalized Plane Wave |
| MOR | Mid-ocean Ridge |
| MOR | Modulus Of Resilience |
| MOR | Modulus Of Rupture |
| MORASS | Multiple Overhauser Relaxation AnalysiS And Simulation |
| MORB | Mid-ocean Ridge Basalt |
| MORBID | Morse Oscillator-rigid Bender Internal Dynamics (hamiltonianin Rotational-vibrational Energy Levels Calcn.) |
| MORD | Magnetic Optical Rotation Dispersion |
| MORE | Micro-optical Ring Electrode |
| MORT | Molecular Orbital Resonance Theory |
| MORTI | Mesopause Oxygen Rotational Temp. Imager |
| MOS | Margin Of Safety |
| MOS | Metal Oxide Semiconductor (FET Devices) |
| MOSAP | Marine Oil Spill Action Plan |
| MOSC | Metal-oxide-semiconductor Capacitor |
| MOSES | Mineral Oil Spill Evaluation System |
| MOSES | Modular Sensor System |
| MOSFET | Metal Oxide Semiconductor Field Effect Transistor |
| MOSHO | Maximum Overlap Symmetry Hybrid Orbital |
| MOSIGT | Metal-oxide Semiconductor Insulated Gate Transistor |
| MOSIS | Metal Oxide Semiconductor Implementation Service |
| MOSMO | Maximum Overlap Symmetry Molecular Orbital |
| MOSO | Maximum Overlap Symmetry Orbital (MO For Mols.) |
| MOSQITO | Modeling Of Stormwater Quality Including Tanks And Overflows |
| MOSS | Multilayer Optical Scanning Spectrometer |
| MOST | Metal Oxide Semiconductor Transistor |
| MOT | Magnetooptical Trap |
| MOT | Multistate Orbital Treatment |
| MOTA | Materials Open Test Assembly |
| MOU | Memorandum Of Understanding |
| MOUSE | Method Of Underground Solute Evaluation |
| MOUSE | Modular Oriented Uncertainty System |
| MOV | Metal-Oxide Varistor |
| MOV | Motor Operated Valve |
| MOVB | MO-valence Bond |
| MOVBET | Molecular Orbital (into) Valence Bond Exponential Transformation |
| MOVFF | Modified Orbital Valence Force Field |
| MOVPE | Metallo-organic Vapor-phase Epitaxy |
| MOVS | Molecular Orbital Valence State |
| MOX | Mixed Oxide |
| MOZAIC | Measurement Of Ozone And Water Vapor By Airbus In-Service Aircraft |
| MOZART | Model For OZone And Related Chemical Tracers |
| MP | Model Potential |
| MP-QMC | Model Potential-quantum Monte Carlo |
| MP2 | Moeller-Plesset Second-order Perturbation Theory |
| MP2(FC) | MP2(frozen Core) Only (outer) Valence Electrons Included In The Approximation |
| MP2(FU) | MP2(full) Inner-core Electrons Are Included In The Approxn. |
| MP2-R12 | MP2 Theory With Terms Linear In Interelectronic Distance (r12) |