=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.
=fōns= (font-), _a spring_: font, fount, fountain (Fr.), fontal.
=fōrm-a=, _shape_; =form-o (formāt-)=, _I shape_: form, formal, formula, perform.
=forti-s=, _steadfast_, _brave_: forti-tude, fortify; through Fr., comfort, effort, force, forte, fort, fortress.
=frag-=, =frang-o= (fract-), _I break_: fragile, fragment, fracture, in-fringe.
=frāter=, _brother_: fraternal, fraternity, fratricide (_caedo_), friar (Fr.).
=frīgidus=, _be cold_; =frīger-are=, _make cold_: frigidity, refrigerate, refrigerant.
=frons= (front-), _forehead_: front, frontal, affront, effrontery and frontier.
=frūg-=, =fru-i= (fruct-), _to enjoy_; =frūg-es=, =fructus=, _fruit_; =frugi=, _useful_: fructify, frugi-ferous, frugi-vorous, fruit, fruition, frugal.
=fŭgi-o= (fŭgit-), _I flee_: fugitive, refuge, subterfuge, febrifuge (_febris_, fever).
=fulge-o= (fuls-), _shine_; =fulmen=, _lightning_: refulgent, fulminate.
=fŭnd-o= (fūs-), _I pour_; =fū-tilis=, _vain_: re-fund (= pay back), fusible, refuse, confuse, effusion, confound and foundry (Fr.), fount (of type), futile.
=fund-us=, _bottom_; =fund-āre= (fundāt-), _to found_: fundament = foundation (Fr.), pro-fundity; Fr., profound, (to) found, (to) founder, fund, refund.
=fung-i= (funct-), _perform_: de-funct, function (Fr.) perfunctory.