| fiery(quick, impulsive, reckless, speedy, hasty) |
| flag |
| flaky(passionate, violent, thoughtless, abrupt, impetuous) |
| fleet-footed(summary, abrupt, rapid, unexpected, instant) |
| flying(fast, brief, summary, abrupt, swift) |
| foolhardy(noun, quick, impulsive, rash, reckless) |
| foolish(adjective, impulsive, reckless, hasty) |
| fretful(adjective, keen, violent, anxious, eager) |
| from left field(expression, idiom, extraordinary, wonderful, shocking) |
| fulminant |
| going(fast, rapid, swift) |
| gone off deep end(expression, idiom, passionate, violent, thoughtless) |
| haphazard(adjective, organization, plan) |
| harefooted(fast, irritable, quick, abrupt, speedy) |
| having short fuse(expression, adjective, idiom, keen, violent) |
| heedless(quick, impulsive, reckless, speedy, hasty) |
| histrionic(affected, melodramatic, theatrical) |
| hot |
| hot-and-cold(passionate, violent, thoughtless, abrupt, impetuous) |
| hot-tempered(adjective, keen, violent, anxious, eager) |