| Term | Definition |
| fickle | (adj) inconstant; not loyal |
| fictitious | (adj) untrue; false |
| fidelity | (noun) loyalty; faithful devotion |
| finale | (noun) the ending |
| finicky | (adj) fussy; difficult to please |
| fission | (noun) process of breaking into parts |
| flagrant | (adj) offensive; outrageous; deliberately shocking |
| flaunt | (verb) to show off |
| flaw | (noun) an imperfection |
| flippant | (adj) disrespectful; frivolous; saucy |
| flounder | (verb) to stumble; to fall; to sink |
| flow | (verb) to move like a liquid; to pour out |
| fluctuate | (verb) to waver; to alternate; to move up and down |
| foreboding | (noun) sense of evil or doom is to come |
| forensic | (noun) relating to legal proceedings |