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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. Temporarily incapable of speaking
   "struck dumb";
   - speechless
    
3. Lacking the power of human speech
   "dumb animals"
    
4. Unable to speak because of hereditary deafness
   - mute, silent
    
5. Devoid of good sense or judgment
   - foolish, daft [Brit, informal], stupid, imbecilic, imbecile

1. Make simpler and less intellectually challenging (in a negative sense)
   - dumb down

Derived forms: dumbed, dumbs, dumbing, dumbest, dumber

See also: absurd, cockeyed [informal], derisory, fond, goofy [informal], harebrained, idiotic, ill-advised, ill-conceived, impolitic, imprudent, inadvisable, inarticulate, insane, laughable, ludicrous, mad, mindless, misbegotten, misguided, nonsensical, preposterous, rattlebrained, rattlepated, ridic [informal], ridiculous, scatterbrained, scatty [Brit, informal], silly, stupid, unadvisable, unadvised, unarticulate, unwise, vacant, vacuous, wacky, whacky, zany

Encyclopedia: Dumb, dumb, dumb, dumb, dumb