coincident vs synchronous

coincident

adj
  • Occurring at the same time. 

  • Being in the same location. 

  • Being in accordance, matching. 

noun
  • Either of multiple simultaneous related incidents 

synchronous

adj
  • At the same time, at the same frequency. 

  • Single-threaded; blocking; occurring in the same thread as other computations, thereby preventing those computations from resuming until the communication is complete. 

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