assured vs dubious

assured

noun
  • An insured person. 

adj
  • Guaranteed; secure. 

  • Self-confident; self-assured; sure. 

dubious

adj
  • Arousing doubt; questionable; open to suspicion. 

  • In disbelief; wavering, uncertain, or hesitating in opinion; inclined to doubt; undecided. 

  • Generally considered imprecise or wrong, but not totally unplayable. 

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