congruence vs harmony

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. 

harmony

noun
  • Agreement or accord. 

  • A literary work which brings together or arranges systematically parallel passages of historians respecting the same events, and shows their agreement or consistency. 

  • A pleasing combination of elements, or arrangement of sounds. 

  • The relationship between two distinct musical pitches (musical pitches being frequencies of vibration which produce audible sound) played simultaneously. 

  • The academic study of chords. 

  • Two or more notes played simultaneously to produce a chord. 

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