preposterous

Synonyms

absurd, asinine, balmy, brainless, cockeyed, crackpot, crazy, cuckoo, daffy, daft, dippy, dotty, fatuous, featherheaded, fool, foolish, half-baked, half-witted, harebrained, inept, insane, jerky, kooky (also kookie), loony (also looney), lunatic, lunkheaded, mad, nonsensical, nutty, sappy, screwball, senseless, silly, simpleminded, stupid, tomfool, unwise, wacky (also whacky), weak-minded, witless, zany;

Antonyms

judicious, prudent, sagacious, sage, sane, sapient, sensible, sound, wise;

Near Antonyms

brainy, bright, clever, intelligent, smart;

logical, rational, reasonable, valid;

well-advised;

Related Words

airheaded, birdbrained, brain-dead, chowderheaded, chuckleheaded, clueless, dense, dim, dim-witted, doltish, dopey (also dopy), dorky [slang], dull, dumb, dunderheaded, empty-headed, fatuous, feebleminded, idiotic (also idiotical), imbecile (or imbecilic), knuckleheaded, lamebrain (or lamebrained), mindless, moronic, oafish, obtuse, opaque, pinheaded, simple, slow, slow-witted, soft, softheaded, thoughtless, thick, thickheaded, unintelligent, vacuous, witless;

fallacious, illogical, invalid, irrational, unreasonable, unreasoning, unsound, weak;

farcical, laughable, ludicrous, ridiculous;

notional;

buffoonish, clownish;

ill-advised, unconsidered, unreasoned;

Phrases

out to lunch;