| fervid | adj. | passionate or zealous | ||
| fescue | n. | pointer of straw, wire, etc. | ||
| fetiparous | adj. | giving birth before the young are fully developed | biology | |
| fetlock | n. | joint on horses between the hoof and the knee or hock; fur tuft growing at this joint | ||
| fettle | v. | to make ready, to prepare | ||
| fettle | n. | condition, state | ||
| fiacre | n. | small four-wheeled horse-drawn carriage for hire | ||
| fichu | n. | triangular woman’s scarf | ||
| fides Punica | n. | treachery, lit. “the faith of the Carthaginians” or “Carthaginian honesty” | Latin | |
| fiducial | adj. | of a fixed point used for comparison; based upon trust | ||
| fiduciary | adj. | of a relationship in which one person holds property on behalf of another | ||
| fifth chain | n. | chain used connecting lead horse to pole when five horses are used in a team | ||
| filé | n. | powdered leaves of sassafras | ||
| filibuster | n. | speech obstructing progress in legislature; unauthorized military adventurer in foreign land; freebooter | ||
| filigree | n. | intricate and delicate decoration made of metal wire; ornate or intricate design | ||
| fillip | n. | motion made by bending last joint of finger or the nail of the finger against the thumb and then suddenly releasing it; to strike with a nail snapped from the end of the thumb | ||
| Fimbulwinter | n. | the harsh three years long summerless winter which precedes the end of the world | ||
| finca | n. | large estate in Spain or Hispano-America | ||
| finical | adj. | finicky | ||
| fipple | n. | mouthpiece of certain recorders and flutes, with a fixed sharp edge against which the blown air is directed | ||
| firedog | n. | andiron | ||
| firk | v. | to move suddenly, to be lively; (obsolete) to cheat | ||
| firkin | n. | small cask for liquids, etc., holding a quarter of a barrel | ||
| firth | n. | narrow sea inlet; estuary | ||
| fishmonger | n. | seller of seafood | ||
| fissiparous | adj. | reproducing by fission | ||
| fixie | n. | fixed-gear bicycle | ||
| fjeld | n. | elevated plateau barren of all except rocks | ||
| flageolet | n. | small flute blown from end with four finger holes atop, and two below | ||
| flagitious | adj. | extremely wicked | ||
| flagroot | n. | root of acorus calamus (of the lily family), with supposed healing and hallucinogenic effects, banned in the U.S. for use in food due to its toxicity | ||
| flam | n. | capricious idea or fancy; falsehood, deceit | ||
| flame cell | n. | specialized excretory cell in very simple invertebrates | ||
| flannelette | n. | napped cotton made to resemble flannel | ||
| flapdoodle | n. | nonsense | ||
| flash house | n. | brothel | slang | |
| flash spoon | n. | spoon-shaped metal fishing lure designed to attract through visual action | ||
| flat | n. | fool, dullard | obsolete | |
| flatlings | adv. | with the flat side | ||
| flatus | n. | intestinal gas | ||
| flavescent | adj. | yellowish, turning a pale yellow | ||
| flavid | adj. | yellow, sulphur yellow | ||
| flaw | n. | sudden wind blast; brief gale or storm; abrupt outburst of feeling | ||
| fleer | v. | to grin or laugh in a rude or coarse manner | ||
| flemish | v. | to coil a rope in a pleasing flat spiral pattern | nautical | |
| Flemish horse | n. | extra footrope along yardarm | nautical | |
| flense | v. | to slice away the fat (from a whale or a seal) | ||
| fleuron | n. | flower-shaped decorative element | ||
| flews | n. | hanging flaps of the upper lips of certain dogs | ||
| flex on | v. | to (sometimes subtly) put someone down by showing your superior skills, ability, or possession | slang |
