frecuentar - to frequent

frenar - to break, to slow down, to restrain

fruncir - to wrinkle, to pucker, to knit

fumigar - to fumigate

fundar - to found, to base

fundir - to melt

fungir - to act (as)

festejarse - to enjoy one's self

fraccionar - break, dissipate

fisgar - pry

facultar - authorize, empower

filtrar - percolate

fortificar - fortify