| Acronym | Meaning |
| MF | Modifying Factor (in Oral RfD) |
| MF | Muffin Tin (potential Energy Function) |
| MFA | Molecular-field Approximation |
| MFAG | Medical First Aid Guide For Use In Accidents Involving Dangerous Goods |
| MFC | Mass Flow Controller |
| MFC | Multi-function Controller |
| MFC | Multiconfigurational Frozen Core (approxn. For Electron-atom Scattering Calcns.) |
| MFE | Magnetic Field Effect |
| MFE | Mercury Film Electrode |
| MFE | Modulated Free Electron Orbital Method |
| MFI | Mean Fluorescence Intensity |
| MFI | Melt Flow Index [of Polymer] |
| MFI | Modified Fouling Index |
| MFM | Magnetic Force Microscopy |
| MFO | Mixed-function Oxidase |
| MFP | Magnetic Field Perturbative (method) |
| MFP | Mean Free Path |
| MFR | Melt Flow Ratio |
| MFRC | Membrane Flux Retention Coefficient |
| MFS | Major Facilitator Superfamily |
| MFS | Molecular Fluorescence Spectroscopy |
| MFVT | Mixed Flow Vectored Thrust |
| MG-FSGO | Multiple Gaussian-floating Spherical Gaussian Orbital Method |
| MGA | Modified Glauber Approxn. (in Atom-particle Scattering) |
| MGD | Million Gallons Per Day |
| MGE | Mobile Genetic Element |
| MGED | Microarray Gene Expression Database |
| MGMS | Molecular Graphics And Modelling Society |
| MGMT | O6-methylguanine-DNA Methyltransferase |
| MGS/TES | Mars Global Surveyor Thermal Emission Spectrometer |
| MGSA | Melanoma Growth Stimulatory Activity |
| MGVB | Modified Generalized Valence Bond |
| MHA | Mott-Hubbard-Anderson (model In Band-structure Calcns.) |
| MHC | Major Histocompatibility Complex |
| MHC | Myosin Heavy Chain |
| MHEMT | Metamorphic High Electron Mobility Transistor |
| MHF | Multiple Hearth Furnace (for Incineration) |
| MHIDAS | Major Hazardous Incident Data Service (from UK Atomic Energy Authority) |
| MHW MO | Mulliken-Helmholz-Wolfsberg Molecular Orbital |
| MI | Mitotic Index |
| MIA | Multiplicative Integral Approxn. (in 2-electron Integral Calcn.) |
| MIA | Multivariate Image Analysis |
| MIAM | Modified Independent-atom Model (for Electron-mol. Scattering) |
| MIAME | Minimum Information About A Microarray Experiment |
| MIAR | Mass Isotopomer Abundance Ratio |
| MIBD | Micro-interferometric Backscatter Detection |
| MIBERS | Multi-ion-beam Reactive Sputtering |
| MIBK | Methyl Isobutyl Ketone |
| MIC | Microbially Induced Corrosion |
| MIC | Methyl Isocyanate |