| eager(adjective, rough, careless, foolish, crazy) |
| fantastic(weak, simple, silly, foolish, thoughtless) |
| fast-and-loose(adjective, careless, careful, rash, reckless) |
| fast and loose(expression, idiom, wild, thoughtless, rash) |
| fatuous(weak, simple, silly, foolish, thoughtless) |
| featherheaded |
| feebleminded(weak, simple, silly, foolish, thoughtless) |
| fiery(careless, quick, thoughtless, impulsive, volatile) |
| foot-in-mouth(adjective, careless, careful, rash, reckless) |
| frenzied(careless, anxious, worried, thoughtless, impulsive) |
| furious(careless, anxious, worried, thoughtless, impulsive) |
| guileless |
| half-baked(weak, simple, silly, foolish, thoughtless) |
| half-witted(weak, simple, silly, foolish, thoughtless) |
| harum-scarum(adjective, careful) |
| headstrong(adjective, careless, anxious, bold, worried) |
| helter-skelter(adjective, wild, thoughtless, irresponsible) |
| hubristic |
| idiotic(adjective, weak, simple, silly, foolish) |
| imbecilic(adjective, weak, simple, silly, foolish) |