initials vs short form

initials

noun
  • An abbreviation of a person's name, constructed by taking the initial letters of first, last, and sometimes middle name(s). See monogram 

short form

noun
  • A word with the same meaning as another formed by removing one or more of the syllables of the longer word, and considered a word in its own right rather than an abbreviation. 

  • Particularly in Slavic languages, a shortened form of the adjective, used predicatively. 

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