caginess       
noun [ U ] uk/ˈkeɪ.dʒi.nəs/ us/ˈkeɪ.dʒi.nəs/
 守口如瓶,讳莫如深
unwillingness to give information
  He is known for his caginess. 他是出了名的口风紧。 
 My question was met with a moment of caginess before he said, “I really don't know". 在我提出问题后,他讳莫如深地说“我真的不知道。” 
 See: cagey
 - More examples
 - One reason for her caginess might be ignorance which she does not want to admit.
 - Clinical studies for new drugs are shrouded in caginess, but most of the companies say they will have results in about a year.
 - There was the usual caginess about the deal's value.