preposterous Synonyms

absurd nonsensical irrational foolish ludicrous laughable cockeyed ridiculous idiotic derisory imbecilic unconscionable tomfool softheaded unachievable unrealizable teratoid stupid sophistic unscientific silly senseless self-contradictory sappy uncredible unlikely cockamamie unthinkable unbelievable fairytale moronic ill-conceived unimaginable harebrained blue sky unreasoning out of the question wrong unreasonable feebleminded risible perverted grotesque fatuous farfetched farcical fantastic fanciful extreme exorbitant