prominence vs unimportance

prominence

noun
  • A bulge: something that bulges out or is protuberant or projects from a form. 

  • The state of being prominent: widely known or eminent. 

  • Autonomous height; relative height or prime factor; a concept used in the categorization of hills and mountains. 

  • A gaseous projection, often loop-shaped, springing from the surface of the Sun or a star. 

  • Relative importance. 

unimportance

noun
  • Lack of importance. 

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