For-bid-den, gwaharddedig, gwarafunedig
For-ci-ble, cadarn, hyrym, nerthol
For-eign-er, alldud, estron
Fore-know-ledge, rhagwybodaeth
For-get-ful, anghofus
For-feit-ure, collediad, fforffediad
For-give-ness, maddeuant, gollyngdod
For-giv-ing, maddeugar; trugarog
For-ma-tion, ffurfiad, lluniad
For-mer-ly, gynt, cyn hyn, er ystalm