synchronicity vs synchrony

synchronicity

noun
  • The state of being synchronous or simultaneous. 

  • Coincidences that seem to be meaningfully related; supposedly the result of "universal forces". 

synchrony

noun
  • synchronicity, the state of two or more events occurring at the same time. 

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