For-tune, tesni; ffyniant; damwain; gwaddol, cynnysgaeth
For-ward, eon; awyddus; hyrwyddo
For-wards, ym mlaen, rhag blaen
Fos-sil, mwm, mettel
Fos-ter, magu, maethu
Found-er, seiliwr: suddo
Foun-tain, ffynnon, ffynnonell
Four-fold, pedwarplyg
Fowl-er, adarwr
Frac-tion, toriad, rhwygiad; twnrif