incongruous vs unmergeable

incongruous

adj
  • Not similar or congruent; not matching or fitting in. 

  • Of two numbers, with respect to a third, such that their difference can not be divided by it without a remainder. 

unmergeable

adj
  • Not mergeable. Incapable of being merged. 

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