dumb  
 adjective uk/dʌm/ us/dʌm/
  (SILENT)      
 C1 哑的;说不出话的
permanently or temporarily unable to speak
  He's been deaf and dumb since birth. 他生下来就又聋又哑。 
 She was struck dumb by what she had seen. 她被自己看到的惊得说不出话来。 
   (STUPID)      
B2 mainly US informal愚蠢的 
stupid 
  Are they brave or just dumb? 他们是勇敢还是愚蠢而已? 
 What a dumb idea! 这想法太蠢了!