co-occurrence vs synchronization

co-occurrence

noun
  • The fact of a thing occurring simultaneously with something else; correlation. 

  • An instance of a thing occurring simultaneously with something else; co-incidence. 

synchronization

noun
  • The state or property of being synchronized. 

  • The arrangement of military actions in time, space, and purpose to produce maximum relative combat power at a decisive place and time. 

How often have the words co-occurrence and synchronization occurred in a corpus of books? (source: Google Ngram Viewer )