Fama, a report; fame, defame, infamy.
Fans (fant-is), speaking; infant [= a non-speaker].
Felix (felīc-is), happy; felicity, infelicity.
Fero, I bear or carry; infer, reference, difference.
Ferrum, iron; ferruginous.
Ferveo, I boil; fervent, effervesce, ferment.
Fido, I trust; confide, infidel, perfidy, diffident.
Filius, a son; filial, affiliation.
Filum, a thread; file, defile, profile.
Finis, an end; final, infinite, confine.