Flecto, I bend; flexible, inflection.
Flos (flōr-is), a flower; floral, Flora, floriculture.
Fluo (fluct-um), I flow; fluent, flux, refluent, fluid.
Forma, a form; form, formal, reform, conformity.
Fortis, strong; fortify, fortitude, fortress.
Frango (fract-um), I break; fragile, fragmentary, infraction.
Frater, a brother; fraternal, fratricide.
Frons (front-is), the forehead; frontispiece, frontal, frontier.
Fruor (fruct-us), I enjoy; fruit, fructify, fruition.