abridgment vs initialism

abridgment

noun
  • An epitome or compend, as of a book; a shortened or abridged form; an abbreviation. 

  • The state of being abridged or lessened. 

  • The leaving out of certain portions of a plaintiff's demand, the writ still holding good for the remainder. 

  • The act of abridging; reduction or deprivation 

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 abridgment and initialism occurred in a corpus of books? (source: Google Ngram Viewer )