chummy vs confidential

chummy

adj
  • Friendly; on, or trying to be on, intimate terms. 

noun
  • Synonym of chum (“friend, pal”) 

  • Nickname for a person, especially a suspect or criminal. 

confidential

adj
  • Kept, or meant to be kept, secret within a certain circle of persons; not intended to be known publicly 

How often have the words chummy and confidential occurred in a corpus of books? (source: Google Ngram Viewer )