asynchronicity vs simultaneity

asynchronicity

noun
  • The extent to which something is asynchronous. 

  • The state of being asynchronous. 

simultaneity

noun
  • 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. 

  • The quality or state of being simultaneous; simultaneousness. 

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