- fileA collection of papers collated and archived together.
- filamentA fine thread or wire.
- filletA headband; a ribbon or other band used to tie the hair up, or keep a headdress in place, or for decoration.
- filigreeA delicate and intricate ornamentation made from platinum, gold or silver (or sometimes other metal) twisted wire.
- defileTo make (someone or something) physically dirty or unclean; to befoul, to soil.
- filiformShaped like or resembling a thread or filament; filamentous.
- fierasferAny of certain fishes of the genus Carapus.
- filaceousComposed of threads, stringy.
- filacerA former officer in the English Court of Common Pleas and the Court of King's Bench, so called because he filed the writs on which he made out process
- filandersA disease in hawks, characterized by the presence of small thread-like worms (probably Capillaria), and of filaments of coagulated blood, stemming from the rupture of a vein.
- filarHaving a thread across the field of view.
- filariaAny of the parasitic nematode worms of superfamily Filarioidea that lives in the blood of vertebrates and is transmitted by insects: the cause of filariasis.
- fileteadoA type of artistic drawing and lettering, incorporating brightly coloured stylised lines, flowers and climbing plants, particularly associated with the city of Buenos Aires, Argentina.
- filiferousProducing or constituting threads.
- filoplumeA hair-like feather; a feather with a slender scape and without a web in most or all of its length.
- filoseTerminating in a thread-like process, or threadlike
- filuma filamentous anatomical structure