| Term | Definition |
| extroverted | (adj) interested in other people and the environment rather than oneself |
| fanatic | (adj/noun) overly enthusiastic (person) |
| fatal | (adj) deadly; destructive |
| fatigue | (noun) exhaustion; weariness; extreme tiredness |
| fauna | (noun) the animals of a specified time period |
| felicitous | (adj) pleasing |
| ferocious | (adj) fierce; savage; violently cruel |
| fervent | (adj) intense; passionate |
| fickle | (adj) inconstant; not loyal |
| fictitious | (adj) untrue; false |
| fidelity | (noun) loyalty; faithful devotion |
| finale | (noun) the ending |
| fission | (noun) process of breaking into parts |
| flagrant | (adj) offensive; outrageous; deliberately shocking |
| flaw | (noun) an imperfection |
| flippant | (adj) disrespectful; frivolous; saucy |
| flounder | (verb) to stumble; to fall; to sink |