coincident vs synchronic

coincident

adj
  • Occurring at the same time. 

  • Being in the same location. 

  • Being in accordance, matching. 

noun
  • Either of multiple simultaneous related incidents 

synchronic

adj
  • Occurring at a specific point in time. 

  • Relating to the study of a language at only one point in its history. 

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