coincident vs concomitant

coincident

noun
  • Either of multiple simultaneous related incidents 

adj
  • Occurring at the same time. 

  • Being in the same location. 

  • Being in accordance, matching. 

concomitant

noun
  • Something happening or existing at the same time. 

  • An invariant homogeneous polynomial in the coefficients of a form, a covariant variable, and a contravariant variable. 

adj
  • Of or relating to the grammatical aspect which expresses that a secondary action is occurring simultaneously to the primary action of the statement. 

  • Accompanying; conjoining; attending; concurrent. 

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