four - gas
- four-decker cage
- four-drum hoist
- four-entry system
- four-leg IFS chock shield support
- four-leg IFS shield support
- four-piece frame set
- four-piece set
- four-ply
- four-point
- four-pointed pigstye
- four-wheeled scraper
- foyaite
- frac pump
- fracking
- fraction
- fractional
- fractional crystalline
- fractional distillation
- fractional load
- fractional number
- fractional precipitation
- fractional select
- fractional shovelling
- fractionate
- fractionator
- fractural tectonics
- fracture
- fracture cleavage
- fracture direction
- fracture ductility
- fracture edge
- fracture face
- fracture face area
- fracture failure
- fracture flow capacity
- fracture fluid loss coefficient
- fracture force
- fracture growth
- fracture height
- fracture initiation
