1. Devoid of good sense or judgment
   "foolish remarks"; "a foolish decision";
   - dumb, stupid, daft [Brit, informal], imbecilic, imbecile
    
2. Having or revealing stupidity
   "ridiculous foolish behaviour";
   - anserine, dopy, dopey, goosey, goosy, gooselike, jerky

See also: absurd, asinine, birdbrained [informal], blockheaded [informal], boneheaded [informal], chuckleheaded [informal], cloddish, cockeyed [informal], dense, derisible, derisory, derp [informal], dim [informal], doltish, dull, dumb, duncical [informal], duncish [informal], dunderheaded [informal], fatheaded [informal], fatuous, fond, gaumless [Brit, archaic, informal], goofy [informal], gormless [Brit, informal], harebrained [informal], idiotic, ill-advised, ill-conceived, impolitic, imprudent, inadvisable, inane, insane, knuckleheaded [informal], laughable, loggerheaded [informal], ludicrous, lumpen, lumpish, mad, mindless, misbegotten, misguided, muttonheaded [informal], nitwitted [informal], nonsensical, obtuse, pea-brained [informal], preposterous, rattlebrained, rattlepated, ridic [informal], ridiculous, scatterbrained, scatty [Brit, informal], senseless, silly, slow, soft-witted, stupid, thick [informal], thickheaded [informal], thick-skulled [informal], thick-witted [informal], unadvisable, unadvised, unintelligent, unthinking, unwise, vacant, vacuous, wacky, weak, whacky, witless, wooden-headed [informal], yokel-like, zany

Antonym: wise

Encyclopedia: Foolish