1. Taking more than usual time to learn or understand; lacking intellectual acuity
   "dumb officials make some really dumb decisions";
   - dense, dim [informal], dull, obtuse, slow
    
2. Lacking the power of human speech
   "dumb animals"
    
3. Unable to speak because of hereditary deafness
   "The dumb child learned to communicate through sign language";
   - mute, silent
    
4. Temporarily incapable of speaking
   "struck dumb";
   - speechless
    
5. Devoid of good sense or judgment
   "That was a dumb decision that cost us the game";
   - foolish, stupid, daft [Brit, informal], imbecilic, imbecile

Derived forms: dumber, dumbest

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

Encyclopedia: Dumb, dumb, dumb, dumb, dumb