speechlessness       
noun [ U ] uk/ˈspiːtʃ.ləs.nəs/ us/ˈspiːtʃ.ləs.nəs/
 无言; 哑口无言
the feeling of being unable to speak because you are so angry, shocked, surprised, etc.
  She was stunned to speechlessness by his marriage proposal. 他的求婚令她目瞪口呆。 
 I was shocked to the point of speechlessness. 我震惊得说不出话来。 
 See: speechless
 - More examples
 - She was reduced to speechlessness by what he told her.
 - He once reduced a senior official to speechlessness by asking him why America needed a Federal Reserve at all.
 - Even Andrew was startled into speechlessness by her outburst.