caesura vs hiatus

caesura

noun
  • A pause or interruption in a poem, music, building, or other work of art. 

  • Using two words to divide a metrical foot. 

  • The caesura mark ‖ or ||. 

  • A break of an era or other measure of history and time; where one era ends and another begins; turning point. 

hiatus

noun
  • An interruption, break or pause. 

  • A gap in a series, making it incomplete. 

  • An opening in an organ. 

  • A gap in geological strata. 

  • A syllable break between two vowels, without an intervening consonant. (Compare diphthong.) 

  • An unexpected break from work. 

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