anonym vs initials

anonym

noun
  • A mere name; a name resting upon no diagnosis or other recognized basis. 

  • An anonymous person. 

  • An assumed or false name; a pseudonym. 

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 

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