diminution vs initialism

diminution

noun
  • The act or process of making diminutive. 

  • A lessening, decrease or reduction. 

  • a compositional technique where the composer shortens the melody by shortening its note values. 

initialism

noun
  • The process of forming words or terms using initial letters of other words. 

  • A term formed from the initial letters of several words or parts of words, which is itself pronounced letter by letter. 

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