| Acronym | Meaning |
| FOCO | First-order Correlation Orbital |
| FOCS | Fiber Optic Chemical Sensor |
| FOCSY | Foldover-corrected Correlation Spectroscopy |
| FODA | Fiber Optic Doppler Anemometry |
| FODLS | Fiber Optic Dynamic Light Scattering |
| FOE | First-order Exchange (in Electron-atom Scattering Calcn.) |
| FOEA | First-order Eikonal Approximation |
| FOEA | First-order Error Analysis |
| FOG | Fats, Oil, And Grease |
| FOGO | Floating Orbital Geometry Optimization |
| FOIA | Freedom Of Information Act |
| FOISD | Fiber Optic Isolated Spherical Dipole Antenna |
| FOJT | First-order Jahn-Teller |
| FOLCI | Fiber Optic Low-coherence Interferometry |
| FOLED | Flexible Organic Light-emitting Device |
| FOLIBS | Fiber Optic Laser Induced Breakdown Spectroscopy |
| FOLZ | First-order Laue Zone |
| FOM | Figure Of Merit |
| FOM | Forced Oscillator Model |
| FOMBT | First-order Many-body Theory |
| FOMP | First Order Magnetization Process |
| FOND | Fiber-optic Neutron Detector |
| FOND PT | Finite-order Nondegenerate Perturbation Theory |
| FONDA | First-order Nondegenerate Adiabatic (theory For Electron-mol. Inelastic Scattering) |
| FONSI | Finding Of No Significant Impact |
| FOPIM | First Order Perturbation Iteration Method |
| FOPPA | First-order Polarization Propagator Approach |
| FOQELS | Fiber Optic Quasi Elastic Light Scattering |
| FOREGS | Forum Of European Geological Surveys |
| FORS | Fully Optimized Reaction Space |
| FOS | Fiber Optic Sensor |
| FOS | First-order Sudden |
| FOSFA | Federation Of Oils |
| FOTOS | First-order Theory Of Oscillator Strength |
| FOURPI | Fourier Path Integral |
| FOWL | Fossil Fuel Waste Leaching (computer Program) |
| FP | Fluorescence Polarizationpar |
| FP | Finite Perturbation |
| FP-LMTO | Full-potential Linear Combination Of Muffin-tin Orbitals |
| FP-MC | Finite Perturbation-multiconfigurational Method |
| FP-SCF-INDO | Finite Perturbation-SCF-INDO |
| FPA | Flavor Profile Analysis |
| FPA | Focal Plane Array |
| FPC | Federal Power Commission |
| FPC | Fish Protein Concentrate |
| FPC | Fixed Partial Charge |
| FPC | Fractional Parentage Coeff. (in Group-theor. Calcns.) |
| FPCLM | Flat Plate Contained Liquid Membrane |
| FPD | Flame Photometric Detector (gas Chromatography) |
| FPD | Flat Panel Display |