| puerile(adjective, silly, foolish, fantastic, unwise) |
| scatterbrained(adjective, frivolous, dizzy, frothy, flighty) |
| batty(noun, adjective, light, silly, stupid) |
| brainless(adjective, foolish, stupid, impractical, half-baked) |
| bonkers(adjective, silly, foolish, unwise) |
| absurd(adjective, light, informal, silly, foolish) |
| barmy(adjective, silly, foolish, unwise) |
| birdbrained(adjective, impractical, frivolous, half-baked, doomed) |
| ditsy(adjective, informal, silly, frivolous, dizzy) |
| flighty(adjective, frivolous, dizzy, frothy, featherbrained) |
| frivolous(adjective, dizzy, frothy, flighty, featherbrained) |
| insane(adjective, silly, foolish, fantastic, unwise) |
| moronic(adjective, foolish, impractical, half-baked, doomed) |
| ludicrous(adjective, light, foolish, stupid, crazy) |
| blockheaded(adjective, foolish, impractical, half-baked, doomed) |
| crackpot(adjective, foolish, impractical, half-baked, doomed) |
| frothy(adjective, frivolous, dizzy, flighty, featherbrained) |
| imbecilic(adjective, foolish, impractical, half-baked, doomed) |
| lunatic(adjective, silly, foolish, unwise) |
| nonsensical(adjective, foolish, stupid, fantastic, senseless) |