WordWeb Online

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

See also: absurd, asinine, cockamamie [N. Amer], cockamamy [N. Amer], cockeyed, derisory, fatuous, fond, goofy, harebrained, idiotic, ill-advised, ill-conceived, impolitic, imprudent, inadvisable, inane, insane, laughable, ludicrous, mad, mindless, misbegotten, misguided, nonsensical, preposterous, rattlebrained, rattlepated, ridiculous, sappy, scatterbrained, scatty [Brit], silly, stupid, unadvisable, unadvised, unwise, vacuous, wacky, whacky, zany

Antonym: wise

Encyclopedia: Foolish