| Term | Definition |
| fallacious | false; misleading |
| fallacy | mistaken idea based on flawed reasoning; invalid argument |
| fallible | liable to err; capable of making an error |
| fallow | plowed but not sowed; uncultivated |
| falter | hesitate |
| fanaticism | excessive zeal; extreme devotion to a belief or cause |
| fancied | imagined; unreal |
| fancier | breeder or dealer of animals |
| fancy | notion; whim; inclination |
| fanfare | call by bugles or trumpets; showy display |
| farce | broad comedy; mockery |
| fastidious | difficult to please; squeamish |
| fatalism | belief that events are determined by forces beyond one's control |
| fathom | comprehend; investigate |
| fatuous | brainless; inane; foolish, yet smug |
| fauna | animals of a period or region |
| fawning | trying to please by behaving obsequiously, flattering or clinging |
| faze | disconcert; dismay; disrupt the composure of |
| feasible | practical |
| febrile | feverish |
| feckless | feeble and ineffective; careless and irresponsible |
| fecundity | fertility; fruitfulness |
| feign | pretend |
| feint | trick; shift; sham; blow |
| felicitous | suitably expressed; well chosen |
| felicity | happiness; appropriateness ( of a remark , choice, etc.) |
| fell (adj) | cruel; deadly |
| fell (v) | cut or knock down; bring down ( with a missile) |
| felon | person convicted of a grave crime |
| feral | not domestic; wild |
| ferment | agitation; commotion |
| ferret | drive or hunt out of hiding |
| fervent | ardent; hot |
| fervid | ardent ; marked by great passion or zeal |
| fervor | glowing ardor; intensity of feeling |
| fester | rankle; produce irritation or resentment |
| festive | joyous; celebratory |
| fete | honor at a festival |
| fetid | malodorous; foul smelling |
| fetter | shackle; confine |
| fiasco | total failure |
| fiat | command; authorization |
| fickle | changeable; faithless |
| fictitious | imaginary |
| fidelity | loyalty |
| figment | invention; imaginary thing |
| figurative | not literal, but metaphorical |
| figurine | small ornamental statuette |
| filch | steal |
| filial | pertaining to a son or daughter |
| filibuster | the use of obstructionist tactics, especially prolonged speechmaking, for the purpose of delaying legislative action. |
| filigree | delicate; lacelike metal work |
| filing | particles removed by a file |
| finale | conclusion |
| finesse | delicate skill |
| finicky | too particular; fussy |
| finite | limited |
| firebrand | hothead; trouble maker |
| fissure | crevice |
| fitful | Happening or appearing now and then: intermittent, occasional, periodic, periodical, sporadic; spasmodic |
| flaccid | flabby |
| flag | droop; grow feeble |
| flagrant | conspicuously wicked; blatant; outrageous |
| flail | thresh grain by hand; strike or slap; toss about |
| flair | talent |
| flamboyant | ornate |
| flaunt | display ostentatiously |
| flay | strip off skin; plunder; whip; attack wit harsh criticism |
| fleck | tiny mark or spot |
| fledgling | inexperienced; novice beginner; neophyte |
| fleece (n) | wool coat of a sheep |
| fleece (v) | rob; plunder |
| flick | light stroke as with a whip |
| flinch | hesitate; shrink |