regularity vs simultaneity

regularity

noun
  • The condition or quality of being regular 

  • A particular regular occurrence 

simultaneity

noun
  • The quality or state of being simultaneous; simultaneousness. 

  • More than one complete musical texture occurring at the same time. This first appeared in the music of Charles Ives, and is common in the music of Conlon Nancarrow, and others. 

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