not clear vs tangible

not clear

tangible

noun
  • A physical object; something that can be touched. 

  • Real or concrete results. 

adj
  • Able to be treated as fact; real or concrete. 

  • Comprehensible by the mind; understandable. 

  • Touchable; able to be touched or felt; perceptible by the sense of touch. 

  • Perceptible; able to be perceived. 

How often have the words not clear and tangible occurred in a corpus of books? (source: Google Ngram Viewer )