adj. 25B6; adjective PREPOSTEROUS, ridiculous, ludicrous, farcical, laughable, risible, idiotic, stupid, foolish, silly, inane, imbecilic, insane, hare-brained; unreasonable, irrational, illogical, nonsensical, pointless, senseless; informal crazy; Brit. informal barmy, daft.
reasonable, sensible.