| fiery(adjective, strong, severe, intense, passionate) |
| firm |
| flipped(adjective, strong, severe, intense, violent) |
| foolhardy(determined, impulsive, stubborn, reckless, heedless) |
| forceful(adjective, passionate, wild, cruel, crazy) |
| frightening(adjective, strong, severe, intense, violent) |
| froward(determined, impulsive, stubborn, reckless, heedless) |
| fulminant(unstable, unpredictable, volatile) |
| fuming(adjective, passionate, violent, wild, excited) |
| haggard |
| hard-core(determined, impulsive, stubborn, reckless, impetuous) |
| hard-nosed(determined, impulsive, stubborn, reckless, impetuous) |
| hard-shell(determined, impulsive, stubborn, reckless, heedless) |
| hazardous(unstable, unpredictable, volatile) |
| heedless(determined, impulsive, stubborn, reckless, impetuous) |
| hog-wild |
| horrible(adjective, strong, severe, intense, violent) |
| immitigable |
| immutable(adjective, hard, severe, rough, harsh) |
| impassioned(adjective, passionate, violent, excited, cruel) |