Pocket Thesaurus
Antonyms of preposterous
insane, unbelievable, excessive, irrational, incredible, unthinkable, fantastic, ludicrous, senseless, unreasonable, crazy, outrageous, stupid, silly, absurd, impossible, laughable, foolish, nonsensical, shocking, asinine, exorbitant, extravagant, extreme, far-out, harebrained, monstrous, out of the question, thick, too much, unusual, wacky, wild, taking the cake
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