fĭd-es, faith; fĭdēlis, fid-us, trusty; foed-us (foeder-), treaty: fidelity, infidel, diffident, feder-al, defy, af-fi-ance, fi-ancé, faith, fealty.
fīlius, son, (fīlia daughter): filial, affiliate, Fitz- (Fitzedward) (Fr.).
fing-o, (fĭct-, fĭg-), I fashion, make up: figment, figure, fictile, fiction, effigy; through Fr., feign, feint, faint.
fīnis, end; fīni-o (fīnīt-), I end: fine, con-fine, final, finable, finical, affinity, infinitude; through Fr., finance, finish, finesse.
firm-us, steadfast; firm-o (firmat-), I strengthen, strength: firm, confirmation, affirmative, firmament (lit. support), farm (through Ang. Sax.).
flagr-o (flagrāt), I burn; flam-ma, flame: flagrant, inflame, flambeau (Fr.).
flect-o (flex-), I bend: in-flect, flex, flex-ible, flexor, flexion, flexure.
flōs (flōr-), flower; floresc-ĕre, to blossom: flora, florid, florist, florescent.
flu-o (flux-), flow; fluct-us a wave: flu-ent, fluid, influence, flux, fluctuate.
fŏli-um, leaf; fŏliāt-us leaved: foliage, folio, foil (Fr.), trefoil, portfolio.