fluorspar - front of thrust
- four-compartment mill
- four-decker cage
- four-electrode array
- four-electrode spread
- four-electrode system
- four-eyed fish
- four-layer apparent-resistivity curve
- four-layer curve
- four-point bit
- four-probe system
- four-wing drilling bit
- four-wing rotary bit
- fourbles
- fourchite
- fourfold symmetry
- Fourier analysis
- Fourier transform migration
- fourling
- fourmarierite
- foveolate