| Acronym | Meaning |
| FGD | Flue Gas Desulfurization |
| FGDIS | Flue Gas Desulfurization Information System |
| FGEF | Federal Geographic Encoding Format |
| FGETS | Food And Gill Exchange Of Toxic Substances |
| FGF | Fibroblast Growth Factor |
| FGFR | Fibroblast Growth Factor Receptor |
| FGGE | First GARP Global Experiment |
| FGH | Fourier-grid Hamiltonian |
| FGHAZ | Fine Grain Heat-affected Zone |
| FGM | Functionally Gradient Materials |
| FGR | Flue Gas Recirculation |
| FGRM | Fourier-grid R-matrix Formalism (in Scattering Problems) |
| FGSE | Field-gradient Spin-echo |
| FHBS | Finite Hilbert Basis Set |
| FHCP | Federal Hazard Communication Program |
| FHMO | Fenske-Hall MO |
| FHNC | Fermi Hypernetted Chain Method (in Quantum Statistics) |
| FHSA | Federal Hazardous Substances Act |
| FI | Field Ionization |
| FI | Fouling Index |
| FIA | Fluorescence Immunoassay |
| FIA | Flow Injection Analysis |
| FIAM | Free Ion Activity Model |
| FIAS | Flow Injection Atomic Spectrometry |
| FIAT | Field Information Agency Technical |
| FIB | Focused Ion Beam |
| FIBC(A) | Flexible Intermediate Bulk Container (Association) [bulk Bag] |
| FIBOS | Focused Ion Beam Optical Spectroscopy |
| FIC | Fractional Inhibitory Concentration |
| FICVS | Flow-injection Cathodic Stripping Voltammetry |
| FID | Flame Ionization Detector (gas Chromatography) |
| FID | Free Induction Decay (Fourier Transform Spectroscopy) |
| FIDA | Fluorescence Intensity Distribution Analysis |
| FIE | Flow-injection Extraction |
| FIFRA | Federal Insecticide |
| FIGE | Field Inversion Gel Electrophoresis |
| FIGLU | Formiminoglutamic Acid |
| FIIA | Flow Injection Immunoassay |
| FIIAA | Flow Injection Immunoaffinity Analysis |
| FIK | Field Ionization Kinetics |
| FILDA | Fluorescence Intensity And Lifetime Distribution Analysis |
| FILOS | Far Infrared Limb Observing Spectrometer |
| FILTER | Filtration And Irrigated Cropping For Land Treatment And Effluent Reuse |
| FIM | Field-Ion Microscopy |
| FIM | Forced Impulse Method (in Atom Ion-impact Ionization) |
| FIM | Friable Insulation Material |
| FIM-APS | Field Ion Microscopy-atom Probe Spectroscopy |
| FIMDA | Fluorescence Intensity Multiple Distributions Analysis |
| FIMS | Fine-split IR Multispectral Scanner (for Remote Sensing) |
| FIMS | Field Ionization Mass Spectrometry |