concord vs congruence

concord

noun
  • Agreement of words with one another, in gender, number, person or case. 

  • A state of agreement; harmony; union. 

  • An agreeable combination of tones simultaneously heard; a consonant chord; consonance; harmony. 

  • A variety of sweet American grape, with large dark blue (almost black) grapes in compact clusters; a Concord grape. 

verb
  • To agree; to act together 

congruence

noun
  • The quality of agreeing or corresponding; being suitable and appropriate. 

  • Matrix similarity by an orthogonal matrix. 

  • A relation between two numbers indicating they give the same remainder when divided by some given number. 

  • More generally: any equivalence relation defined on an algebraic structure which is preserved by operations defined by the structure. 

  • The quality of being isometric — roughly, the same measure and shape. 

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